# Shadow detail/gamma enhancement for the analog sources



## tse

It's designed! A circuit for enhancing shadow detail in analog sources. It will do the same thing as the circuit in an earlier thread except this one doesn't have to be direct coupled with the back porch at zero volts. This one does require a horizontal or composite sync input along with the RGB video.


The DC restore circuit took more time than I thought it would and was more difficult, too. The availability of video/sync processing chips seems to be shrinking. No more LM2202s out there. This is probably better because all the parts can be had from Newark, Mouser, etc. They're cheap, too.


The original thread:

http://www.avsforum.com/avs-vb/showt...1&page=1&pp=30


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## tse

The rest of the schematic.


If anyone wants the Orcad files, yell. I'll be happy to send them. You can go to the Orcad web site and download a demo of their software. It works but restricts you to small designs.


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## Ericglo

Let me be the first to say congratulations, tse!!!


Ericglo


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## PAW

Now how does that saying go "Build it and they will come."


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## misohorny

Thankyou tse.



Since I'm currently in Europe, I am trying to track down a Yamakawa 375, which I understand is a Momitsu v880 clone, with a better built case (and remote). Has anyone scoped the analog RGB from a sigma EM8500 based dvd player to determine if tse's original ESD circuit can be added while doing an output stage/ BNC mod i.e. the back porch is at zero volts?


Cheers,


John


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## mp20748

Quote:

Originally Posted by *misohorny*
Thankyou tse.



Since I'm currently in Europe, I am trying to track down a Yamakawa 375, which I understand is a Momitsu v880 clone, with a better built case (and remote). Has anyone scoped the analog RGB from a sigma EM8500 based dvd player to determine if tse's original ESD circuit can be added while doing an output stage/ BNC mod i.e. the back porch is at zero volts?


Cheers,


John
That circuit would be a serious help for the Momitsu (as well as any other source). It would be nice to have it as an external device before the projector, as well as, an input card version for the well known CRT's.


So far, it seems to be the cure for that linear gamma problem that's commom with most CRT projectors.


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## ecrabb

How hard would it be to get boards made? I'm comfortable sourcing components, soldering, and sticking stuff in a case, but I'm clueless on where or how to get PCB's made. Wasn't there a sort of "automated" prototyping/small-quantity site where you could upload files and get back finished boards pretty reasonably? I'd love to try one of these, but I'm on a pretty strict budget these days.


Thanks for your hard work tse - I can't wait to see how this works with my own eyes.


SC


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## garyfritz

MP, do you happen to know if the Momitsu's have a non-0V porch? I measured mine and it sure looked like 0V to me, but I'm no expert at reading video waveforms.


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## jtnfoley

Quote:

Originally Posted by *ecrabb*
How hard would it be to get boards made? I'm comfortable sourcing components, soldering, and sticking stuff in a case, but I'm clueless on where or how to get PCB's made. Wasn't there a sort of "automated" prototyping/small-quantity site where you could upload files and get back finished boards pretty reasonably? I'd love to try one of these, but I'm on a pretty strict budget these days.


Thanks for your hard work tse - I can't wait to see how this works with my own eyes.


SC



Four layer, solder mask and silkscreen rapid turn shop:
http://www.expresspcb.com/ExpressPCBHtm/Costs.htm 
http://www.expresspcb.com/ExpressPCBHtm/Specs.htm 


They've got their own downloadable schematic and routing software.

I'm taking delivery of some of their "Production" series 2 layer boards this week for a work project. I'll let you know how the quality works out.


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## WTS

Hi tse,

Good work,

So have you built some boards and tested this on a pj. Which pj did you test it on and how much of an improvement did you notice.


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## ChrisWiggles

Quote:

So far, it seems to be the cure for that linear gamma problem that's commom with most CRT projectors.
Mike: curious what you mean by this? I think some of the digital guys have been trying to emulate the linear tail, because I believe it's written into the standards now.


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## Javers

Wow, this looks fab! tse any ideas on how much bandwidth these circuits can handle?


Jon


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## misohorny

Quote:

Originally Posted by *ChrisWiggles*
Mike: curious what you mean by this? I think some of the digital guys have been trying to emulate the linear tail, because I believe it's written into the standards now.


Chris, You mean to say you've been a member since 2002 and you haven't noticed the number of threads where members with CRT projectors have been frustrated when, having calibrated their projectors in every way possible, they were still unable to obtain satisfactory black detail (linear gamma). The most likely reason I've read posted being the somewhat unpredictable CRT tube light output at low level, compounded by the effect of wear.

It would seem you have been spreading yourself too thin, contributing as you do so much to the digital projector forums as well.


For research purposes could you tell me which digital projector you have been watching lately? It would help when I collate the evidence that proves my theory that watching digital projectors causes psychosis.


Cheers,


John


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## darinp2

Great stuff. So, is somebody going to make these? I'll just throw out that if you are looking for somebody to hand build some maybe moome would be a good person for it. I liked the transcoder I bought from him and he seems to have done some other good stuff.


I know at least one person who I think would be interested in this for a CRT and I would like to see the results.


--Darin


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## Clarence

Nice work tse.


Has anyone already created a bill of materials with component pricing and sources?


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## misohorny

Good idea Darinp2.


I think tse has done a brilliant job, and single handedly. He has provide the details, for those of us who enjoy the thrill of DIY, and if he partners with someone to manufacture these modules he is also catering to the "sell me one" members. With the detail made public improvements may come more quickly, although tse seems to be more than capable, solo.


John


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## dlarsen

Quote:

Mike: curious what you mean by this? I think some of the digital guys have been trying to emulate the linear tail, because I believe it's written into the standards now.
The linear tail is spec'd for Rec.709 gamma. Iâ€™ve not seen it specâ€™d (or desired?) for degamma (the display). Seems the Rec.709 degamma targets displays @ 2.5. for an overall 1.13 Have you seen the standards mention it in respect to displays? (degamma)


Dave


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## WTS

Hi Darin,


Actually I've included the tse circuit in my transcoder design which will be on the new Moome card, but only for the transcoder section not the HDMI section.


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## ChrisWiggles

Quote:

For research purposes could you tell me which digital projector you have been watching lately? It would help when I collate the evidence that proves my theory that watching digital projectors causes psychosis.
barco 808. last time i checked it was a crt. but maybe i should check again. har...


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## tse

Quote:

Originally Posted by *ecrabb*
How hard would it be to get boards made? I'm comfortable sourcing components, soldering, and sticking stuff in a case, but I'm clueless on where or how to get PCB's made. Wasn't there a sort of "automated" prototyping/small-quantity site where you could upload files and get back finished boards pretty reasonably? I'd love to try one of these, but I'm on a pretty strict budget these days.


Thanks for your hard work tse - I can't wait to see how this works with my own eyes.


SC
I'm working on a PCB layout and should have it finished soon. Will upload the files needed for getting boards. I use a Canadian company that charges about $47 for set-up then a couple of bucks per square inch. They only make the boards in pairs. Two of them will cost about $90.

www.apcircuits.com 


If anyone knows of a place that is cheaper than this let me know.


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## tse

Quote:

Originally Posted by *WTS*
Hi tse,

Good work,

So have you built some boards and tested this on a pj. Which pj did you test it on and how much of an improvement did you notice.
Not tested yet. I did build the green channel on the first design then discovered that my video sources do not have the back porch at zero volts. Doh! That's really the reason for the DCR version.


If your source does have the back porch clamped at zero volts the first version will work fine and be cheaper.


This circuit has been proven at my last job before VDC. The project there was developing a liquid crystal light valve projector that required an "S" shaped gamma correction with enhance at the dark video parts (like this project) as well as enhance in the brighter video levels.


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## tse

Quote:

Originally Posted by *Javers*
Wow, this looks fab! tse any ideas on how much bandwidth these circuits can handle?


Jon
Though I have yet to test the bandwidth I expect 200MHz.


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## tse

Quote:

Originally Posted by *Clarence*
Nice work tse.


Has anyone already created a bill of materials with component pricing and sources?
It's not yet finished. I've used common parts that can be had from many sources like Newark, Mouser, etc. Nothing exotic here. Should be fairly cheap to build.


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## Clarence

Quote:

Originally Posted by *tse*
I'm working on a PCB layout and should have it finished soon. Will upload the files needed for getting boards. I use a Canadian company that charges about $47 for set-up then a couple of bucks per square inch. They only make the boards in pairs. Two of them will cost about $90.


If anyone knows of a place that is cheaper than this let me know.
What about $51 for 3 boards in the link posted above?

http://www.expresspcb.com/ExpressPCBHtm/Costs.htm


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## jtnfoley

Quote:

Originally Posted by *Clarence*
What about $51 for 3 boards in the link posted above?

http://www.expresspcb.com/ExpressPCBHtm/Costs.htm
[ignorance]

Perhaps four layer is needed, as the big honkin groundplane would be handy for stifling interferance?

[/ignorance]

If so, the costs will be markedly higher...
http://www.expresspcb.com/ExpressPCB...erStandard.htm 

$130 + ($0.87 * NumberOfBoards * BoardAreaInSquareInches) + ($1.25 * NumberOfBoards) + Shipping.
http://www.expresspcb.com/ExpressPCB...Production.htm 

$260 + ($0.66 * NumberOfBoards * BoardAreaInSquareInches) + ($1.00 * NumberOfBoards) + Shipping.


If two layer will work, perhaps the ProtoPro service:
http://www.expresspcb.com/ExpressPCB...csProtoPro.htm 

Production style, soldermask and silkscreen, for a fixed price of $179 for four boards.



I'll have a few of their "Production" boards in my hot little hands today for an office project. I'll report on the quality.
http://www.expresspcb.com/ExpressPCB...Production.htm


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## jtnfoley

The boards I'm getting are from 4PCB.com and will be here tomorrow or friday, not expresspcb. Apparently, 4PCB was preferred by my EE management.
http://www.4pcb.com/pcb_milling_low_...tm#convenience 


One interesting feature from these guys is a free gerber checker upload tool, FreeDFM


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## Hiller131

Quote:

Originally Posted by *jtnfoley*
The boards I'm getting are from 4PCB.com and will be here tomorrow or friday, not expresspcb.
Advanced Circuits (4PCB.com) is great as far as cost. I have run into a couple of problems with them at work but for personal stuff I use them all the time.


Good boards cheap and they run specials all the time.


Steve


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## Clarence

 http://img189.imageshack.us/img189/7546/tse01mux7qp.gif 

Clamp R14 2.2K

Clamp R19 10K

Clamp R20 100

Clamp R21 50K variable

Clamp C16 100pF

Clamp C17 100nF

Clamp C18 100pF

Clamp U9A 74HC4538

Clamp U9B 74HC4538


In the â€œMiscâ€ circuit, I renamed (in red) the duplicate C5 to C22:
http://img189.imageshack.us/img189/6...e02misc7ka.gif 

Misc C5 22uF

Misc C22* 22uF

Misc C19 100nF

Misc D3 1N4002

Misc D4 1N4002

Misc F1 RXE040

Misc F2 RXE040

Misc J101 RawPwrIn 8v 15v

Misc J102 RegPwr 5v

Misc U3B/C/D 74HC86

Misc U4 MC7805

Misc U5 MC7905

http://img189.imageshack.us/img189/2...03clamp7pm.gif 

Mux C13 100nF

Mux C14 100nF

Mux U8 74HC4053


In the â€œVideoâ€ circuit, I renamed (in red) the duplicate â€œR1â€ to â€œR7â€:
http://img189.imageshack.us/img189/8101/tse04vid4vh.gif 

VID_R R1 2.4K

VID_R R7* 120

VID_R R2 430

VID_R R3 360

VID_R R4 75

VID_R R5 75

VID_R R6 75

VID_R R13 47K

VID_R C1 1000pF

VID_R C2 1000pF

VID_R C3 10uF

VID_R C4 10uF

VID_R C5 10uF

VID_R C6 1000pF

VID_R C7 1000pF

VID_R C8 10uF NP

VID_R D1 SD101A

VID_R D2 SD101A

VID_R U2 HFA1100

VID_G R1 2.4K

VID_G R7* 120

VID_G R2 430

VID_G R3 360

VID_G R4 75

VID_G R5 75

VID_G R6 75

VID_G R13 47K

VID_G C1 1000pF

VID_G C2 1000pF

VID_G C3 10uF

VID_G C4 10uF

VID_G C5 10uF

VID_G C6 1000pF

VID_G C7 1000pF

VID_G C8 10uF NP

VID_G D1 SD101A

VID_G D2 SD101A

VID_G U2 HFA1100

VID_B R1 2.4K

VID_B R7* 120

VID_B R2 430

VID_B R3 360

VID_B R4 75

VID_B R5 75

VID_B R6 75

VID_B R13 47K

VID_B C1 1000pF

VID_B C2 1000pF

VID_B C3 10uF

VID_B C4 10uF

VID_B C5 10uF

VID_B C6 1000pF

VID_B C7 1000pF

VID_B C8 10uF NP

VID_B D1 SD101A

VID_B D2 SD101A

VID_B U2 HFA1100

http://img189.imageshack.us/img189/1...e05sync4fg.gif 

Sync C6 100nF

Sync C7 100nF

Sync C8 10nF

Sync C15 1nF

Sync D7 SD101A

Sync D8 SD101A

Sync J7 BNC

Sync J8 BNC

Sync R4 1K

Sync R6 1K

Sync R10 22K

Sync R11 22K

Sync R13 4.7K

Sync R16 10

Sync R18 47K

Sync R23 100

Sync U3A 74HC86

Sync U6 LM311

http://img189.imageshack.us/img189/5852/tse06sh3se.gif 

SH_R C9 330nF

SH_R C10 10nF

SH_R C11 100nF

SH_R C12 100nF

SH_R R2 10K

SH_R R3 33K

SH_R R7 2.2K

SH_R R8 4.7K

SH_R R12 100

SH_R R15 160K

SH_R R17 10K

SH_R R22 10K

SH_R R33 2.7K

SH_R U7A/B TL082

SH_G C9 330nF

SH_G C10 10nF

SH_G C11 100nF

SH_G C12 100nF

SH_G R2 10K

SH_G R3 33K

SH_G R7 2.2K

SH_G R8 4.7K

SH_G R12 100

SH_G R15 160K

SH_G R17 10K

SH_G R22 10K

SH_G R33 2.7K

SH_G U7A/B TL082

SH_B C9 330nF

SH_B C10 10nF

SH_B C11 100nF

SH_B C12 100nF

SH_B R2 10K

SH_B R3 33K

SH_B R7 2.2K

SH_B R8 4.7K

SH_B R12 100

SH_B R15 160K

SH_B R17 10K

SH_B R22 10K

SH_B R33 2.7K

SH_B U7A/B TL082


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## Clarence

 http://img189.imageshack.us/img189/7546/tse01mux7qp.gif 
Clamp R14 2.2K

Clamp R19 10K

Clamp R20 100

Clamp R21 50K variable

Clamp C16 100pF

Clamp C17 100nF

Clamp C18 100pF

Clamp U9A 74HC4538

Clamp U9B 74HC4538


In the â€œMiscâ€ circuit, I renamed (in red) the duplicate C5 to C22:
http://img189.imageshack.us/img189/6...e02misc7ka.gif 

Misc C5 22uF

Misc C22* 22uF

Misc C19 100nF

Misc D3 1N4002

Misc D4 1N4002

Misc F1 RXE040

Misc F2 RXE040

Misc J101 RawPwrIn 8v 15v

Misc J102 RegPwr 5v

Misc U3B/C/D 74HC86

Misc U4 MC7805

Misc U5 MC7905

http://img189.imageshack.us/img189/2...03clamp7pm.gif 

Mux C13 100nF

Mux C14 100nF

Mux U8 74HC4053


In the â€œVideoâ€ circuit, I renamed (in red) the duplicate â€œR1â€ to â€œR7â€:
http://img189.imageshack.us/img189/8101/tse04vid4vh.gif 

VID_R R1 2.4K

VID_R R7* 120

VID_R R2 430

VID_R R3 360

VID_R R4 75

VID_R R5 75

VID_R R6 75

VID_R R13 47K

VID_R C1 1000pF

VID_R C2 1000pF

VID_R C3 10uF

VID_R C4 10uF

VID_R C5 10uF

VID_R C6 1000pF

VID_R C7 1000pF

VID_R C8 10uF NP

VID_R D1 SD101A

VID_R D2 SD101A

VID_R U2 HFA1100

VID_G R1 2.4K

VID_G R7* 120

VID_G R2 430

VID_G R3 360

VID_G R4 75

VID_G R5 75

VID_G R6 75

VID_G R13 47K

VID_G C1 1000pF

VID_G C2 1000pF

VID_G C3 10uF

VID_G C4 10uF

VID_G C5 10uF

VID_G C6 1000pF

VID_G C7 1000pF

VID_G C8 10uF NP

VID_G D1 SD101A

VID_G D2 SD101A

VID_G U2 HFA1100

VID_B R1 2.4K

VID_B R7* 120

VID_B R2 430

VID_B R3 360

VID_B R4 75

VID_B R5 75

VID_B R6 75

VID_B R13 47K

VID_B C1 1000pF

VID_B C2 1000pF

VID_B C3 10uF

VID_B C4 10uF

VID_B C5 10uF

VID_B C6 1000pF

VID_B C7 1000pF

VID_B C8 10uF NP

VID_B D1 SD101A

VID_B D2 SD101A

VID_B U2 HFA1100

http://img189.imageshack.us/img189/1...e05sync4fg.gif 

Sync C6 100nF

Sync C7 100nF

Sync C8 10nF

Sync C15 1nF

Sync D7 SD101A

Sync D8 SD101A

Sync J7 BNC

Sync J8 BNC

Sync R4 1K

Sync R6 1K

Sync R10 22K

Sync R11 22K

Sync R13 4.7K

Sync R16 10

Sync R18 47K

Sync R23 100

Sync U3A 74HC86

Sync U6 LM311

http://img189.imageshack.us/img189/5852/tse06sh3se.gif 

SH_R C9 330nF

SH_R C10 10nF

SH_R C11 100nF

SH_R C12 100nF

SH_R R2 10K

SH_R R3 33K

SH_R R7 2.2K

SH_R R8 4.7K

SH_R R12 100

SH_R R15 160K

SH_R R17 10K

SH_R R22 10K

SH_R R33 2.7K

SH_R U7A/B TL082

SH_G C9 330nF

SH_G C10 10nF

SH_G C11 100nF

SH_G C12 100nF

SH_G R2 10K

SH_G R3 33K

SH_G R7 2.2K

SH_G R8 4.7K

SH_G R12 100

SH_G R15 160K

SH_G R17 10K

SH_G R22 10K

SH_G R33 2.7K

SH_G U7A/B TL082

SH_B C9 330nF

SH_B C10 10nF

SH_B C11 100nF

SH_B C12 100nF

SH_B R2 10K

SH_B R3 33K

SH_B R7 2.2K

SH_B R8 4.7K

SH_B R12 100

SH_B R15 160K

SH_B R17 10K

SH_B R22 10K

SH_B R33 2.7K

SH_B U7A/B TL082


----------



## Clarence

 http://img189.imageshack.us/img189/7546/tse01mux7qp.gif 
Mux C13 100nF

Mux C14 100nF

Mux U8 74HC4053


In the â€œMiscâ€ circuit, I renamed (in red) the duplicate C5 to C22:
http://img189.imageshack.us/img189/6...e02misc7ka.gif 
Misc C5 22uF

Misc C22* 22uF

Misc C19 100nF

Misc D3 1N4002

Misc D4 1N4002

Misc F1 RXE040

Misc F2 RXE040

Misc J101 RawPwrIn 8v 15v

Misc J102 RegPwr 5v

Misc U3B/C/D 74HC86

Misc U4 MC7805

Misc U5 MC7905

http://img189.imageshack.us/img189/2...03clamp7pm.gif 
Clamp R14 2.2K

Clamp R19 10K

Clamp R20 100

Clamp R21 50K variable

Clamp C16 100pF

Clamp C17 100nF

Clamp C18 100pF

Clamp U9A 74HC4538

Clamp U9B 74HC4538


In the â€œVideoâ€ circuit, I renamed (in red) the duplicate â€œR1â€ to â€œR7â€:
http://img189.imageshack.us/img189/8101/tse04vid4vh.gif 
VID_R R1 2.4K

VID_R R7* 120

VID_R R2 430

VID_R R3 360

VID_R R4 75

VID_R R5 75

VID_R R6 75

VID_R R13 47K

VID_R C1 1000pF

VID_R C2 1000pF

VID_R C3 10uF

VID_R C4 10uF

VID_R C5 10uF

VID_R C6 1000pF

VID_R C7 1000pF

VID_R C8 10uF NP

VID_R D1 SD101A

VID_R D2 SD101A

VID_R U2 HFA1100

VID_G R1 2.4K

VID_G R7* 120

VID_G R2 430

VID_G R3 360

VID_G R4 75

VID_G R5 75

VID_G R6 75

VID_G R13 47K

VID_G C1 1000pF

VID_G C2 1000pF

VID_G C3 10uF

VID_G C4 10uF

VID_G C5 10uF

VID_G C6 1000pF

VID_G C7 1000pF

VID_G C8 10uF NP

VID_G D1 SD101A

VID_G D2 SD101A

VID_G U2 HFA1100

VID_B R1 2.4K

VID_B R7* 120

VID_B R2 430

VID_B R3 360

VID_B R4 75

VID_B R5 75

VID_B R6 75

VID_B R13 47K

VID_B C1 1000pF

VID_B C2 1000pF

VID_B C3 10uF

VID_B C4 10uF

VID_B C5 10uF

VID_B C6 1000pF

VID_B C7 1000pF

VID_B C8 10uF NP

VID_B D1 SD101A

VID_B D2 SD101A

VID_B U2 HFA1100

http://img189.imageshack.us/img189/1...e05sync4fg.gif 
Sync C6 100nF

Sync C7 100nF

Sync C8 10nF

Sync C15 1nF

Sync D7 SD101A

Sync D8 SD101A

Sync J7 BNC

Sync J8 BNC

Sync R4 1K

Sync R6 1K

Sync R10 22K

Sync R11 22K

Sync R13 4.7K

Sync R16 10

Sync R18 47K

Sync R23 100

Sync U3A 74HC86

Sync U6 LM311

http://img189.imageshack.us/img189/5852/tse06sh3se.gif 
SH_R C9 330nF

SH_R C10 10nF

SH_R C11 100nF

SH_R C12 100nF

SH_R R2 10K

SH_R R3 33K

SH_R R7 2.2K

SH_R R8 4.7K

SH_R R12 100

SH_R R15 160K

SH_R R17 10K

SH_R R22 10K

SH_R R33 2.7K

SH_R U7A/B TL082

SH_G C9 330nF

SH_G C10 10nF

SH_G C11 100nF

SH_G C12 100nF

SH_G R2 10K

SH_G R3 33K

SH_G R7 2.2K

SH_G R8 4.7K

SH_G R12 100

SH_G R15 160K

SH_G R17 10K

SH_G R22 10K

SH_G R33 2.7K

SH_G U7A/B TL082

SH_B C9 330nF

SH_B C10 10nF

SH_B C11 100nF

SH_B C12 100nF

SH_B R2 10K

SH_B R3 33K

SH_B R7 2.2K

SH_B R8 4.7K

SH_B R12 100

SH_B R15 160K

SH_B R17 10K

SH_B R22 10K

SH_B R33 2.7K

SH_B U7A/B TL082


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## Phil Smith

Ignorant question: Why does device do a better job of lower ire gamma adjustment than a HTPC video card? I ask because this is great if it works and I want to build one!


TSE, maybe you could offer a kit. That way you could make some well earned money for all your work.


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## GEBrown

Clarence,


Your post makes perfect sense to me!!!


YEAH RIGHT!!!


What the heck is all that stuff?


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## techman707

Quote:

Originally Posted by *ChrisWiggles*
barco 808. last time i checked it was a crt. but maybe i should check again. har...
Chris, you're just suffering from radiation poisoning.


----------



## garyfritz

Quote:

Originally Posted by *Phil Smith*
Ignorant question: Why does device do a better job of lower ire gamma adjustment than a HTPC video card?
I'm not sure it DOES do a better job than an HTPC. But for those of us who don't HAVE an HTPC, this is an attractive option!


----------



## misohorny

Quote:

Originally Posted by *techman707*
Chris, you're just suffering from radiation poisoning. 
Actually techman,


judging by Chris' informed posts in the Digital Hi-End Projectors Forum, he's far from a digital virgin. I'll have to footnote the amnesiac effects in my thesis.  


John


----------



## Clarence

Hope I don't sound like a [email protected], but might I suggest keeping the name calling confined to the other 2 gamma threads that spiraled off topic.


It looks like TSE did a great job with these circuits and I'd hate to see a third thread ruined.


----------



## jtnfoley

Quote:

Originally Posted by *Clarence*
Hope I don't sound like a [email protected], but might I suggest keeping the name calling confined to the other 2 gamma threads that spiraled off topic.


It looks like TSE did a great job with these circuits and I'd hate to see a third thread ruined.
I'll second that... I have the wherewithall to build these beauties and want to see this tse design to conclusion (or at least gerber files!)


----------



## misohorny

Quote:

Originally Posted by *Phil Smith*
Why does device do a better job of lower ire gamma adjustment than a HTPC video card? I ask because this is great if it works and I want to build one!
Phil,

This circuit is a gamma adjustment circuit, it adjusts a part of the gamma curve. HTPCs adjust the whole gamma curve, although I'm sure algorythms like Rec.709 could be easily implimented in video card drivers to tweak the gamma curve too.


Clarence,

Just stirring, but your point is taken.


Cheers,


John


----------



## Clarence

Quote:

Originally Posted by *misohorny*
Clarence,

Just stirring, but your point is taken.
Thanks John. I like slinging OT jabs too, but I didn't want tse to get frustrated by the heckling.


----------



## GEBrown

Quote:

Originally Posted by *WTS*
Hi Darin,


Actually I've included the tse circuit in my transcoder design which will be on the new Moome card, but only for the transcoder section not the HDMI section.
Would you care to share more info on the new Moome card?


Thanks!!


----------



## tse

Quote:

Originally Posted by *Phil Smith*
Ignorant question: Why does device do a better job of lower ire gamma adjustment than a HTPC video card? I ask because this is great if it works and I want to build one!


TSE, maybe you could offer a kit. That way you could make some well earned money for all your work.
It won't do a better job than a HTPC video card. That's going to be alot more flexible than this circuit. What this will do is give people that only have DVD and HDTV receiver analog sources a way to enhance the shadow detail and set the black level at true black.


----------



## tse

Clarence,


Nice job on the parts list. Damn, there's that many parts in this thing?


----------



## Clarence

Yeah, lots of parts... expecially when you list them separately for the RG&B circuits.


Can you verify that C17 is 100*n*F?

Clamp C16 100pF

Clamp C17 100nF

Clamp C18 100pF


Also, for what it's worth, I tried to get a WAG on the component costs

(not including the resistors and capacitors... are there any listed that would cost more than about a dime?)Clamp U9A 74HC4538 $1.17 http://www.newark.com/NewarkWebComme...KU=38C1094&N=0 

Clamp U9B 74HC4538 $1.17 http://www.newark.com/NewarkWebComme...KU=38C1094&N=0 

Misc U3B/C/D 74HC86 $1.10 http://www.newark.com/NewarkWebComme...KU=38C1097&N=0 

Clamp R14 2.2K $0.49 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Sync U3A 74HC86 $1.10 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Misc D3 1N4002 $0.03 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Clamp R21 50K variable $2.55 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_R U2 HFA1100 $3.45 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_G U2 HFA1100 $3.45 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_B U2 HFA1100 $3.45 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Sync U6 LM311 $2.60 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Misc F1 RXE040 $0.24 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_R D1 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_G D1 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_G D2 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_B D1 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

VID_B D2 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Sync D7 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

Sync D8 SD101A $0.05 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

SH_R U7A/B TL082 $1.50 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

SH_G U7A/B TL082 $1.50 http://www.newark.com/NewarkWebComme...&Ntk=gensearch 

SH_B U7A/B TL082 $1.50 http://www.newark.com/NewarkWebComme...&Ntk=gensearch


----------



## tse

Clarence,


C17 is 100nF, C16 and 18 are 100pF.


Your prices look about right. I'll post a parts list soon.


----------



## tse

The gerber files and the pcb file.


*.gb0 is solder side

*.gb1 is component side

*.gb15 is top silkscreen/board outline

*.nc is drill drawing

www.apcircuits.com has a free gerber viewer as do most pcb web sites. There was mention of another earlier in the thread. Remember, you import gerber files into the program not open them like most programs do.


Comments, suggestions are welcome. I did this layout manually and I always make a mistake or two. Look it over, if you like, and tell me what you think. I'm going to wait a couple of days before I send it out for boards.


If you want to look at the PCB file, the demo for the program that I used is located at www.waldherr.com It's a neat little program.

 

AVSGamDCR.zip 206.5400390625k . file


----------



## jtnfoley

Quote:

Originally Posted by *tse*
The gerber files and the pcb file.

*.gb0 is solder side

*.gb1 is component side

*.gb15 is top silkscreen/board outline

*.nc is drill drawing
www.apcircuits.com has a free gerber viewer as do most pcb web sites. There was mention of another earlier in the thread. Remember, you import gerber files into the program not open them like most programs do.

Comments, suggestions are welcome. I did this layout manually and I always make a mistake or two. Look it over, if you like, and tell me what you think. I'm going to wait a couple of days before I send it out for boards.

If you want to look at the PCB file, the demo for the program that I used is located at www.waldherr.com It's a neat little program.


I've taken the liberty of uploading these files onto the freedfm service at 4pcb... I should have a response whether their automated checker spots any troubles shortly...


--Edit: There it is:

--Edit2: The autochecker found and fixed silkscreen line width problems (they require 7 mil line widths) which may result in less readability.

 

TSE-001 Gamma Correction Circuit.pdf 28.1435546875k . file


----------



## tse

Neat! $7.00 each for a hundred if you can wait four weeks. That's not bad.


Two boards from AP Circuits will cost about $90 and they don't have solder mask or silkscreen. But. I only need one so I think it's still the best deal.


----------



## jtnfoley

Quote:

Originally Posted by *tse*
Neat! $7.00 each for a hundred if you can wait four weeks. That's not bad.


Two boards from AP Circuits will cost about $90 and they don't have solder mask or silkscreen. But. I only need one so I think it's still the best deal.
Let me check with PCB Express... the $51/3 deal may apply with this board size, 2 layers.


----------



## jtnfoley

The 4PCB boards arrived for my work project... They look good (no solder mask, which makes the silkscreen hard to read...)


At lunchtime I'll look into getting pcbexpress to quote what I've taken to calling the TSE-001 Gamma Circuit.


----------



## tse

The quote from AP Circuits for two boards:


AP CircuitsÂ® Basic Prototype Estimate


2 circuit boards of 3.4" x 8.2" on FR4 .062"

(8.6 cm x 20.8 cm)

No soldermasks, no legends, shear cut


--------------------------------------------------------------------------------


Lot Charge $46.00

FR4 .062" Materials Fee $36.24

Extra Drills Fee $0.00

Drilled Slots Fee $0.00

High Density Drilling Fee $0.00

Bottom Legend Fee $0.00

Milled Slots Fee $0.00


--------------------------------------------------------------------------------


Estimate Total $82.24 US*


--------------------------------------------------------------------------------


*Shipping and handling charges not included.

*Applicable taxes not included.




They ship Fed Ex next day which adds $20.00


----------



## jtnfoley

The ExpressPCB "ProtoPro" service may prove a better price/performance point... four production-style (soldermask and silkscreen included) boards for $179USD.
http://www.expresspcb.com/ExpressPCB...csProtoPro.htm 
Quote:

ProtoPro boards have top and bottom copper layers with all holes plated through. They also include top and bottom soldermask layers giving the boards a green color. On the top surface is a white silkscreen layer showing the component outlines. The solder mask layers give the boards a very professional appearance.


ProtoPro designs must fit in a 21 sq-in rectangle and no dimension can exceed 12". With each order, we send you 4 identical boards.
Sounds like cleaner, prettier boards, with a two day turnaround.


----------



## jtnfoley

OK, ExpressPCB (using their focmula and volume discount structure from their web site) would be $8.80USD per board plus shipping for 100 pieces with a 10 day turnaround ("Production" boards.)

Quantities from 50-99 would be $9.21 each, and from 2-49 would be $14.76.. this is far better than 4PCBs' $23-$42 each in 5-10 quantities.


This board is too big for the as-advertised 3 for $51.00 price.


----------



## Clarence

Quote:

Originally Posted by *tse*
The gerber files and the pcb file.


*.gb0 is solder side

*.gb1 is component side

*.gb15 is top silkscreen/board outline

*.nc is drill drawing

www.apcircuits.com has a free gerber viewer as do most pcb web sites. There was mention of another earlier in the thread. Remember, you import gerber files into the program not open them like most programs do.


Comments, suggestions are welcome. I did this layout manually and I always make a mistake or two. Look it over, if you like, and tell me what you think. I'm going to wait a couple of days before I send it out for boards.


If you want to look at the PCB file, the demo for the program that I used is located at www.waldherr.com It's a neat little program.
If anyone just wants a quick peek at some of the Gerber files:

http://img361.imageshack.us/img361/1369/tsepcb3hu.gif 

http://img361.imageshack.us/img361/5452/tsegreen0io.gif


----------



## jtnfoley

ExpressPCB requires the board layout be done in their software, which has no import/export functionality. Bizarre, and business limiting. Oh well.


----------



## jtnfoley

Back to 4PCB... They called me for a follow-up to determine if an order would be forthcoming... I mentioned that a short run of prototypes would be first with a more quantities later.


Sales0chick mentioned two specials they are running (I get the impression that there is always something special going on here...)

1) 3 for 33 special... $99USD for three two-layer boards with soldermask and silkscreening.

2) 2 for 4 special... Four week price on two week turnaround.


The 3 for 33 each pricing is quite a bit better price and appearance than any of the proto costs I've seen thusfar.


----------



## MTyson

How can I do something like this with my HTPC? I use FFDShow for gamma correcton right now, but it adjusts the whole gamma curve and not just part of it, correct? When I adjust it to get acceptable shadow detail I no longer get absolute black during a fade to black.


What can I get to help my HTPC do what this thing that TSE has made does? Certain video card? Modded video card? What?


I woud like to have absolute black again if I could, but right now the cost is just too much (black crush).


Thanks


----------



## tse

Quote:

Originally Posted by *jtnfoley*
Back to 4PCB... They called me for a follow-up to determine if an order would be forthcoming... I mentioned that a short run of prototypes would be first with a more quantities later.


Sales0chick mentioned two specials they are running (I get the impression that there is always something special going on here...)

1) 3 for 33 special... $99USD for three two-layer boards with soldermask and silkscreening.

2) 2 for 4 special... Four week price on two week turnaround.


The 3 for 33 each pricing is quite a bit better price and appearance than any of the proto costs I've seen thusfar.
That does sound like a good deal. I'll check it out.


Thanks


----------



## ChrisWiggles

Quote:

How can I do something like this with my HTPC? I use FFDShow for gamma correcton right now, but it adjusts the whole gamma curve and not just part of it, correct? When I adjust it to get acceptable shadow detail I no longer get absolute black during a fade to black.
1) Avoid using the FFDshow gamma adjustments, I believe it only operates in 8-bit. This will introduce banding problems.


2) depending on your video card, you should use that. Nvidia has good simple gamma adjustment, as well as I believe many have more advanced adjustments allowing you to make spaghetti out of your gamma curve if you so desire! It also makes these adjustments at I believe 10 bits at least, so this helps avoid banding.


When you are adjusting gamma, be sure to do it sparingly, and view bright scenes as well. Many times people will adjust gamma while looking at dark scenes, and keep seeing more and more shadow detail and raise their gamma curve far too much. What you are doing is crushing the contrast in the bright portions of the image and your depth will suffer and things will look postery and flat in bright scenes. The better way to do it is to move back and forth between a dark scene and a bright scene and find a good interplay between shadow detail and depth/contrast in bright scenes. Also, if you figure your CRT has a gamma of close to 2.5, you can just shoot for a target gamma maybe .2 or .3 less than that. If you have a non-LC machine, you will want to have a slightly lower final gamma number than an LC machine, because of the lower ANSI contrast (this means raising the gamma curve in the electronics more). An LC machine will maintain shadow details better, so there is less of a need to try to elicit low-end detail, and so you can be more conservative with your gamma adjustments.


----------



## benny

G'day Folks,


following TSE's initial posting on using electronics to replace the typical video card gamma correction function, it got me thinking that a mate of mine who heads a local electronics design company here in Melbourne might be able to knock up something similar. I added a couple of 'wish list' items to the original concept and yesterday he showed me what has been working on for the last couple of weeks in his spare time.


It uses the same Intersil HFA1100's at its core that TSE uses in his design (he researched alternates but concluded that those OP-amps were the best chips appropriate), and has added functionality for variable gain, response curve and setup level. We set the prototypes up feeding a NEC 9PG Xtra that I maintain and the results were very promising. After a short time we were able to pretty well replicate the gamma function of the ATI Radeon 9600 card that normally feeds the projector. It was pleasing to note that the posterization and background noise that normally accompanies using high gamma values in the video card were reduced using the electronics solution. My mate is still fine tuning some of the component values on the board but it's looking like a viable alternative for those folks who don't use a HPTC to drive their projectors.


When I next catch up with him I'll try and remember to take some piccies of the cro traces showing the difference between input and output, but in the meantime here's a couple of piccies of the prototypes sprawled across his "testbench"


Cheers 


Russ

http://www.users.bigpond.net.au/benn..._proto_01b.jpg 
http://www.users.bigpond.net.au/benn..._proto_02b.jpg


----------



## tse

That's way neater than my test bench! Sent the pcb files off to APCircuits today. Looking forward to recieving the pcbs about wednesday. Stuffing them and testing will happen later. This weekend will be taken up by the gun show in Melbourne. Soon the heat will die down and range time can commence.


----------



## Ericglo

benny,

That is great. This is looking like a very nice solution.


tse,

Are you and CJ related or the same person? You both like guns and CRTs. For me, I have gotten the guns(weapons) removed from my system after my stint as an armorer in the Marines.


Ericglo


----------



## jtnfoley

Quote:

Originally Posted by *Ericglo*
benny,

That is great. This is looking like a very nice solution.


tse,

Are you and CJ related or the same person? You both like guns and CRTs. For me, I have gotten the guns(weapons) removed from my system after my stint as an armorer in the Marines.


Ericglo
PLEASE keep this thread on track! I had a thread of my own closed ("What (other) expensive hobbies...") when it devolved into a firearms debate.


----------



## WTS

Hi Russ,


He's got a whack of opamps on those boards, I see five, a few more tse's circuit requires. Are we going to see some schematics for his design.


Thanks


----------



## misohorny

Is introducing this kind of circuit, or one more complex, likely to cause audio-sync problems? Are those building test circuits, testing for this too?



John


----------



## WTS

THis will add no delays to the video.


----------



## benny

Quote:

Originally Posted by *WTS*
Hi Russ,


He's got a whack of opamps on those boards, I see five, a few more tse's circuit requires. Are we going to see some schematics for his design.


Thanks
Hi Walter ...


The extra opamps allow for greater flexability and control over the output curve. The final design may well end up with only 4 but you have to start somewhere .... that's what prototypes are for. Build one .. see how it performs in realworld situations rather that just in modeling software, then refine it until it meets all design criteria. As such it's a bit premature to be discussing circuit designs.


My mate has the resources at his disposal to churn out a batch of these using the companies automated SMD layout and soldering machines so the economics of scale may prove beneficial if there is enough interest in this project from fellow forum members to justify the effort in setting up the initial automation data. Costs would be kept to a minimum and the skills required to solder SMD components would be negated.


I'll discuss these points with him and report back.


Cheers 


Russ


----------



## tse

The satellite receiver was offline this evening due to a big thunder boomer off to the south so I broke out an old movie, Wishmaster...Make your wish. Watched the beginning and thought "this would be a good movie to test the gamma circuit with. The very beginning is a bunch of white text on a black background. I'll use this to set the brightness so the background is totaly black. The next scenes are really dark where you miss alot of the detail unless you turn the brightness up quite a bit. This should be a good test for the circuit.


----------



## tse

Quote:

Originally Posted by *WTS*
THis will add no delays to the video.
Not to be picky but it will add a nanosecond or two of delay. I doubt that you will notice.


----------



## WTS

Well, I guess I could have said the same, but it has no real bearing on whether you'll end up with lip sync problems or not. I would think lip sync problems would need delays of at least 100mS or more.


----------



## Ericglo

Quote:

Originally Posted by *jtnfoley*
PLEASE keep this thread on track! I had a thread of my own closed ("What (other) expensive hobbies...") when it devolved into a firearms debate.
Umm, sorry.  I believe I was one of the biggest supporters of tse and his board in the beginning.



Ericglo


----------



## jtnfoley

Quote:

Originally Posted by *Ericglo*
Umm, sorry.  I believe I was one of the biggest supporters of tse and his board in the beginning.



Ericglo
Appologies, I didn't mean to be harsh... This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.


----------



## WTS

Hi Russ,


So does that mean he won't share/post his schematics, just make the boards and sell them.


----------



## misohorny

Quote:

Originally Posted by *jtnfoley*
This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.
Actually the second thread wasn't closed. It just became remarkably quiet when this thread started. Even the loons realised the only reason it was being read was to keep up with developments in tse's circuit.



John


----------



## tse

The bare circuit boards were at my door this evening. FedEX stopped by yesterday but didn't leave them even though I filled out the form saying it was ok to leave stuff last time around. Oh well. Anyhow they're here. Plan to work on them this weekend. The parts list is almost finished. Newark's web site wasn't working right or it would have been finished last night.


Cheers


----------



## WTS

Hi tse,


Well you be sure and let us know they perform now.


----------



## tbrunet

Quote:

Originally Posted by *jtnfoley*
Appologies, I didn't mean to be harsh... This is literally the third thread for the "tse gamma circuit"... Alan G had to close the previous two when the lunatics hijacked the threads with passionately ignorant posts that were WAY off-topic.
Why don't you ask "tse" if the subject of gamma, is or is "not" related to his project? In fact, if you read tse's postings, he seemed to be fairly interested according to his own comments!

tse's project is designed around the near black gamma linearity issue?


thomas


----------



## jtnfoley

Quote:

Originally Posted by *tbrunet*
Why don't you ask "tse" if the subject of gamma, is or is "not" related to his project? In fact, if you read tse's postings, he seemed to be fairly interested according to his own comments!


thomas 
I think you missed the beginning of that exchange... Ericglo made a post which was terminated by a joke regarding firearms (IIRC,) hence my reaction. Two prior threads of Tse's on this topic were closed and aborted because of off-topic posts inspiring lunacy.

I don't want to become this thread's [email protected] vigilante but I _do_ want to see boards fabbed!


----------



## tse

I wish that I hadn't brought up the trip to Melbourne. Sorry everybody. It does suck when a thread that people are interested in disolves into chaos.


Anyhow, the boards are here and I started stuffing them on friday and soon realized that I didn't have all the resistors that I needed. Everything else was here but I overlooked the easy stuff. So the resistors will be here next week and the board should be working by then.


----------



## darinp2

Quote:

Originally Posted by *tse*
Anyhow, the boards are here and I started stuffing them on friday and soon realized that I didn't have all the resistors that I needed. Everything else was here but I overlooked the easy stuff. So the resistors will be here next week and the board should be working by then.
What source device(s) do you plan to use for testing this? One reason I ask is because the stock JVC 30ks seem to have some issues near black, like not passing blacker-than-black and maybe more that Mike Parker has mentioned. Do you have any 1080i component sources (like an HD-TIVO)?


--Darin


----------



## tse

The only decent source is 480p from an Avia DVD player. That's my main interest though I'm soon going to get satellite HDTV.


----------



## tse

The green channel and the DC restore stuff is together.


A few pictures.


A stairstep pattern with the top trace being the input, the bottom is the output.


A finer stairstep pattern.


A multiburst pattern with the highest frequency burst just before the blanking interval at 125MHz.


Sorry about the bad quality of some of the pictures.


----------



## tse

A quick shot of the board.


----------



## WTS

Hi tse,


Looking good, but hey, no smd components. So what are the R values you're using for the scope pics.


----------



## tse

Finished stuffing the board this evening and hooked it up to the projector. With the brightness set so the blacks are totally black I can see details in the darker scenes that before had me adjusting the brightness up. One thing that is different is that in one scene that was dark and smokey some "banding" was visible that I've never seen before. It's definately a move in the right direction.


----------



## Deja Vu

The problem with "gamma correction" is that it will likely reveal the limitations of DVD, especially poorer transfers. By boosting gamma (contrast for the darker areas of the image) all sorts of artifacts can potentially rear their ugly heads and so one should be aware that this isn't a panacea for black level issues. Raising black level (brightness) doesn't seem to cause as many problems, but of course it defeats our objective.


Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.


Cheers,


Grant


----------



## Person99

Quote:

Originally Posted by *Deja Vu*
Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.
The Lumagen has 5 point (100, 80, 50, 30, and 20 IRE). Unfortunately, none of these do it in small increments way down low like tse's solutions, so his should be a better solutions that these.


Dave


----------



## misohorny

Quote:

Originally Posted by *Deja Vu*
The problem with "gamma correction" is that it will likely reveal the limitations of DVD, especially poorer transfers. By boosting gamma (contrast for the darker areas of the image) all sorts of artifacts can potentially rear their ugly heads and so one should be aware that this isn't a panacea for black level issues. Raising black level (brightness) doesn't seem to cause as many problems, but of course it defeats our objective.


Denon DVD players (some of the more expensive ones) have ten point gamma correction and this might just be the tool some of us are looking for.


Cheers,


Grant
Grant,

Your post seem a little confused, TSEs circuit fiddles with gamma, which you say is a bad thing, you then recommend instead a dvd player that fiddles with gamma . There may be some merit to your "artifacts" argument, but I'll wait to see what image the circuit actually produces. The banding tse sees may be a result of over boosting the signal, so as to better see the IRE range the circuit effects.


EDIT:Remember, the aim of the circuit (I understand) is to be able to tweak the output of the projector to fit the standard display device gamma curve (2.20) the source material was (should have been) transferred in expectation of, not to twist the gamma curve like a pretzel, or adjust the gamma of the whole curve to reveal black detail.


EDIT: If limits in the quality of the source material are revealed by the fix, the solution would be to improve (or at least blame) the source, not to blame the circuit, or the projector.


John


----------



## tse

The "banding" phenomenon might not show up with quality equipment. I was using my $59 EBay special Avia DVD player with 480p output. It has a nice picture but 10 bit? Maybe not.


----------



## Mark_A_W

Quote:

Originally Posted by *misohorny*
Grant,

Your post seem a little confused, TSEs circuit fiddles with gamma, which you say is a bad thing, you then recommend instead a dvd player that fiddles with gamma . There may be some merit to your "artifacts" argument, but I'll wait to see what image the circuit actually produces. The banding tse sees may be a result of over boosting the signal, so as to better see the IRE range the circuit effects.


EDIT:Remember, the aim of the circuit (I understand) is to be able to tweak the output of the projector to fit the standard display device gamma curve (2.20) the source material was (should have been) transferred in expectation of, not to twist the gamma curve like a pretzel, or adjust the gamma of the whole curve to reveal black detail.


EDIT: If limits in the quality of the source material are revealed by the fix, the solution would be to improve (or at least blame) the source, not to blame the circuit, or the projector.


John


Grant is spot on. MPEG2 is a perceptual encoding system - there's all sorts of junk hidden just below the level of perception for a "normal" system.


If you boost gamma too high you will see macroblocking and crap that is meant to be hidden.


I boost gamma a bit on my PC (1.1 or 1.2 on the Ati control panel, 1.15 on powerstrip. But if you go too far you will see junk in a dark scene.


----------



## misohorny

Mark ,

I didn't say Grant was wrong, I pointed out we aren't trying to boost gamma too high, we are correcting the output of the projector to match a 2.2 gamma curve, isn't that an ideal "normal" system? One the DVDs should be transferred to match?


EDIT: tse did you do a greyscale calibration with the circuit in place, or was this basically a test to see if the circuit works?


John


----------



## Mark_A_W

Yup, now you're spot on


----------



## misohorny




----------



## darinp2

Quote:

Originally Posted by *tse*
The green channel and the DC restore stuff is together.


A few pictures.


A stairstep pattern with the top trace being the input, the bottom is the output.
Thanks. I'm a little bit confused about these. What range are they showing? If it is from 0%stim to 100%stim then these are different than I was expecting. I thought these were going to affect just things under 5%stim (or so) as much as possible and try to leave the rest of the gamma curve mostly intact. If it is raising up the curve even up to 40% stim or so then this is different and I think it would lower the 3-Dimensionality in many mixed scenes. But then it may just be that I'm not understanding what this is showing, as I mentioned.


--Darin


----------



## tse

The images do show 0 to 100%. So far it looks pretty good but I am going to move the "expansion" down a bit lower and increase the amount of gain. A couple of resistor value changes.


The TL082 opamps proved to be a poor choice. I lucked out on the green channel but the red and blue had a bit of an offset error that led to the video being clamped at about 50mV above zero volts. LT1213 would be a better choice.


----------



## tse

I'm going to drag it out one more time and then I'll leave it alone. If you are not using HTPC or other sources that allow gamma adjustment, this circuit will make a significant difference. It has always been necessary to turn up the brightness level with your CRT projector to see the details in shadows and dark scenes. Then when a "black" scene comes along you notice a gray raster up on your screen. I've been watching my 480P DVD for about a week now with the gamma circuit working and with the projector brightness adjusted so the shadow detail is present the projector goes completely black on black scenes. There is a noticable improvement in dynamic range.


----------



## Person99

Sign me up!


----------



## WTS

Hi tse,


Sounds like it working like you expected. Did you redo the values to move the expansion down and change the gain, what values are you using now.


What opamp are you using now instead of the TL082, maybe try the TLE2082, its the newest version of the old TL0 series.


Walter


----------



## tse

Quote:

Originally Posted by *WTS*
Hi tse,


Sounds like it working like you expected. Did you redo the values to move the expansion down and change the gain, what values are you using now.


What opamp are you using now instead of the TL082, maybe try the TLE2082, its the newest version of the old TL0 series.


Walter
Walter,


The original values are still there. It looks good like it is but I'll probably play around with it before all is said and done. The opamps that control the DC restore level (TL082) were a poor choice because their input offset voltage could be 10 or 13mV! Any dual op-amp with input offset less than 1.0mV and a slew rate better than about 4V/uS should work just fine. For best results pin 5 of those opamps should be connected directly to ground and eliminate the two 10K resistors that go between +/-5V. There was one mistake on the circuit board. I missed connecting pin 1 of the LM311 comparator to ground.


Person99,


All the information except the parts list is at the start of this thread. I'll be happy to help if you would like to build one for yourself.


Scott



Scott


----------



## WTS

Hi Scott,


I thought there was mention made that the values were alittle hot, too much correction and thats why you were going to knock them down abit. So how does this differ from an actual gamma circuit in what it gives you at the end of the day so to speak.


Ouch, 10 - 13mV of input offset, thats terrible for a fet input opamp, I can't remember the last time I looked at the specs for that series but I wouldn't have guessed that bad. Yeah you don't need a super performer for that app but one thing you do want is good dc specs.


----------



## Person99

Quote:

Originally Posted by *tse*
Person99,


All the information except the parts list is at the start of this thread. I'll be happy to help if you would like to build one for yourself.
Thanks, I was hoping we could co-ordinate the run of boards here or if someone wanted to build them and plop them in a case and sell the (in other words, you--to make some money to reimburse the time spent).


If not, I'll just order boards and stuff them myself.


Dave


----------



## Ericglo

I think MP has an interest in this. Whether that interest is building a MPtse unit, I don't know. CJ is close by. Maybe tse and CJ could hook up and build some units.


Ericglo


----------



## benny

G'day 


I mentioned in an earlier post about the progress my mate was making with his solution to this gamma problem and he has now finalised the design. He's incorporated all 3 colour circuits onto the one board and it will be powered by a standard powerpack that is universally available in any country.


Below is a diagram depicting the range of adjustments available via the internal pots. The blue line is the maximum you can get out of it and one of the adjustment pots allows a curve anywhere between this blue one and the straight line to be created. The green is a curve of 2.0 for example. The point where the curves meet at the top (which is 1.0V on this diagram) can be adjusted as well to being it down to the correct 100IRE level (0.7V for example ). This will benefit some projectors which like a slightly higher input signal.


It should be obvious that this is a true gamma correction circuit and should be of particular benefit to those not running a HTPC. It will still be of significant value to those using a HTPC as the curve is infinately variable and exhibits less noise at the bottom end.


This project is a labour of love essentially but he has indicated he is prepared to run off a small batch of these and assemble them into a small case if numbers are sufficient to warrant it. He has access to an automated SMD assembly machine and can produce these for minimal cost. The pricing would depend upon the interest shown so if you are considering something like this shoot me a PM or indicate on this thread. He's not out to make a profit from this venture but wants to cover his costs. Initial thoughts are that he can produce the whole assembly for under US$200.


When I next catch up with him i'll take a piccie of the final circuit board and some CRO traces. For those who don't know one end of a soldering iron from another this will provide an alternative to TSE's design.


Cheers


Russ

http://www.users.bigpond.net.au/benn...ut_curves2.jpg


----------



## PAW

I'd be interested in either design. Though I don't full understand gamma or the technical details, I'm all for better details in the shadows with cranking the brightness.  I know which end of the soldering iron to hold  but I'm more the toaster repairer than the electronics builder.  I'm sure I could find some one to build tse's design but a turn key product is more my style. 


I'd also like to see a few reviews of tse's and benny's mate's designs. Not that I don't trust either of you guys. I just value other opinions before I lay down my hard earned cash.


Russ - what's the input and output of your mate's design (RGBHV, component, VGA. etc.)? OK! I reviewed the thread from the beginning and found the test bench pics. Looks like input & outputs are BNC for RBG. I assume the H & V are handled also?


tse - I'd ask the same question. I see 4 BNC connectors and plug in connector.


----------



## tse

Quote:

Originally Posted by *PAW*
I'd be interested in either design. Though I don't full understand gamma or the technical details, I'm all for better details in the shadows with cranking the brightness.  I know which end of the soldering iron to hold  but I'm more the toaster repairer than the electronics builder.  I'm sure I could find some one to build tse's design but a turn key product is more my style. 


I'd also like to see a few reviews of tse's and benny's mate's designs. Not that I don't trust either of you guys. I just value other opinions before I lay down my hard earned cash.


Russ - what's the input and output of your mate's design (RGBHV, component, VGA. etc.)?


tse - I'd ask the same question. I see 4 BNC connectors and plug in connector.
My board has RGB and Hsync inputs. There are RGB and Hsync outputs. I think both projects are attacking the same problem. Low shadow detail without elevating the black level to a "gray' level. This is something that has been missing from the very beginning of CRT projectors. Wish I had thought this up five years ago when I could have made major bucks from it.


----------



## garyfritz

I'm still a bit unclear why this is a fundamental issue with CRTs. Is the gamma on CRTs just basically wrong for proper shadow detail? Due to the physics of the phosphors or whatever? If that was the case, I don't understand why at least some CRT manufacturers didn't incorporate a gamma correction circuit in their projectors. Guess they weren't really aiming them at the video market, and the target market didn't worry too much about shadow detail?


----------



## Tom.W

In my case it is not using an HTPC or a scaler per say with gamma adjustments . Put me down for one when a universal working unit is available !


----------



## tse

Quote:

Originally Posted by *garyfritz*
I'm still a bit unclear why this is a fundamental issue with CRTs. Is the gamma on CRTs just basically wrong for proper shadow detail? Due to the physics of the phosphors or whatever? If that was the case, I don't understand why at least some CRT manufacturers didn't incorporate a gamma correction circuit in their projectors. Guess they weren't really aiming them at the video market, and the target market didn't worry too much about shadow detail?


The CRT is not a linear device. A certain drive level will produce a certain light output but doubleing the drive does not necessarily double the light output. CRTs are most non-linear at the lower light output end. I'm not sure why the CRT projector seems to aggravate this situation but it has always been thus. A little boost in the shadow detail part of the video helps.


----------



## stylinlp

There are a few HTPC experts on this forum and I would think they have this issue nailed using the newest Radeon or nVidia 6600GT forceware drivers.

The gerneral concensus so far is to leave video card levels alone and do all the tweeking in Theater Tek.


From what you all said, this electronic device can fix the signal levels in such a way that the HTPC video card cannot? Right now I switch my VGA output from the video card to an Extron which converts it to 5BNC cables. What would you do in this configuration?


Oops. The answer to my question was also answered above. Sorry


----------



## ChrisWiggles

Quote:

From what you all said, this electronic device can fix the signal levels in such a way that the HTPC video card cannot? Right now I switch my VGA output from the video card to an Extron which converts it to 5BNC cables. What would you do in this configuration?
No, this card is for users who don't have other means of gamma adjustment in their system, i.e. they are using HD boxes, upconverting players etc etc that don't have high quality(if at all) gamma adjustments. If you are using an HTPC, you can tweak gamma in the video card quite easily and implemented well.


----------



## Phil Smith

Quote:

Originally Posted by *stylinlp*
There are a few HTPC experts on this forum and I would think they have this issue nailed using the newest Radeon or nVidia 6600GT forceware drivers.

The gerneral concensus so far is to leave video card levels alone and do all the tweeking in Theater Tek.
My TheaterTek with 6600GT doesn't have gamma adjustment. TT2 had gamma control when I was using a 9700 Pro video card, but when I installed the 6600GT, that feature disappeared.


----------



## Mark_A_W

Phil do you have Gamma in the display properties? If not, try Powerstrip.


----------



## ChrisWiggles

Indeed Phil, it should be on the card, adjust there.


----------



## Deja Vu

Benny's diagram shows that his particular device affects the entire gamma curve, much like adjusting gamma in TT or with a HTPC's video card - no? Does TSE's device affect the entire gamma curve or does it key in on the lower part only? Denon has some DVD players that allows one to adjust 10 points along the gamma curve for a very precise adjustment. Panasonic's solution I think is similar to a HTPC and effects the entire curve or most of it.


Don't some Barcos have gamma correction?


Gamma correction is a necessity for both CRTs and digital. IMO, since the gamma for CRTs is less than ideal to begin with and digital tries to emmulate CRTs gamma curve then digital is also out to lunch. Some digital projectors do offer some choice of gamma correction which is as step in the right direction.


A couple of questions for someone who might know - Can DVDs be encoded differently so that a fade to black would actually be a fade to black on a CRT and therefore we wouldn't have to resort to gamma correction to try to achieve TFTB while trying to avoid crushing blacks? Is gamma correction basically adjusting contrast in the bottom end of the video with less and less effect as you get into the midrange?

One last question - does increasing gamma put any additional strain on a CRT's tubes?


Cheers,


Grant


----------



## ChrisWiggles

Quote:

Gamma correction is a necessity for both CRTs and digital. IMO, since the gamma for CRTs is less than ideal to begin with and digital tries to emmulate CRTs gamma curve then digital is also out to lunch. Some digital projectors do offer some choice of gamma correction which is as step in the right direction.
I do not necessarily agree with this assessment. Target gamma is for CRT, and I do not know what you mean when you say CRT gamma "is less than ideal." Usually, it is the digital projector's gamma that is incorrect in not matching the CRT gamma curve. Understand that when adjusting gamma on a CRT projector, you usually are moving *away* from the ideal curve, but it is because pushing the natural CRT gamma curve will obscure shadow detail because of ANSI washout.


The point isn't to adjust the gamma because the gamma is wrong, it is because ANSI is weak, we are making adjustments in gamma to compensate for low ANSI contrast, not because there is anything "wrong" with the gamma curve.

Quote:

Can DVDs be encoded differently so that a fade to black was actually a fade to black on a CRT so we wouldn't have to resort to gamma correction to try to achieve TFTB while trying to avoid crushing blacks?
This is something that has been discussed, and yes I think it's possible for full black scenes, but it gets more complicated with anything but full black. In any case I don't think it's really feasible as per standards, and in any case it is not occurring now.

Quote:

Is gamma correction basically adjusting contrast in the bottom end of the video with less and less effect as you get into the midrange?
A simple full-gamma adjust will affect everything obviously. You can try more advanced adjustments to more affect just the lower end, but something has to give somewhere to keep a continuous curve between black and white, so if you are increasing the slope from black for better contrast, somewhere that slope has to decrease. Spreading it out over the whole curve in a simple adjust is easiest, and it spreads out that decrease over the largest area.


----------



## WTS

Hi Benny,

So where is the schematic for the design.


----------



## tse

As no other projects were pending I spent some time playing with the response of the circuit today. The 120 ohm was changed to 75 ohm and the 430 ohm became a 510 ohm. That gave the first "step" in the 16 step stairstep pattern about 20% more amplitude than the original values. It is probably too much but the black bands at the top and bottom of my DVD image are zero light, none and the shadow detail is plenty. Between scenes the projector goes totally black.


----------



## picree

I would be interested in a one of these if things work out and I have a neighbor that would like one as well.


Could someone summarize?-


Parts list is at the beginning of the thread (with some minor adjustments like that noted above).?.?.


Best place to go is 4pcb.com....or are others in this thread planning on coordinating a bulk order from somewhere for the pcb?.?.?


Are others looking at getting just the pcb or a complete pcb with all the parts soldered on?


Picree


----------



## Deja Vu

Chris,


Thanks for the response.


Cheers,


Grant


----------



## Tom.W

If there is someone that could build one of these for me ? if so please let me know.I sold my soldering station awhile back and my hands are not as steady as the used to be.Getting older is a ***** but its better then the alternative  Anyways it is cheaper to buy more than one board and of course I would cover the cost plus time putting the board together.

I would love to try this with the MP modded Neo and Momitsu and the MP-5 

Just send me a PM.


----------



## benny

Quote:

Originally Posted by *PAW*
I'd also like to see a few reviews of tse's and benny's mate's designs. Not that I don't trust either of you guys. I just value other opinions before I lay down my hard earned cash.


Russ - what's the input and output of your mate's design (RGBHV, component, VGA. etc.)? OK! I reviewed the thread from the beginning and found the test bench pics. Looks like input & outputs are BNC for RBG.
Completely understandably about having someone review it. When the final design is built up (soon) I'll be taking it to a few of the local CRT'ers for comments.


Connections will be 3 x BNC's IN and OUT and a socket for a powerpack to plug into. The Sync leads can remain undisturbed.


Quote:

Originally Posted by *Deja Vu*
Benny's diagram shows that his particular device affects the entire gamma curve, much like adjusting gamma in TT or with a HTPC's video card - no?
That is essentially correct Grant. Some more expansion of the very lower IRE levels has been incorporated also but not so much that it effects the overall dynamics of the image. This solution permits very fine adjustments of the curve, whereas the video drivers in the HTPC scenario generally have much coarser adjustments. At least the ATI's do .... I haven't had much exposure to the nVidia cards as yet.


Quote:

Originally Posted by *WTS*
Hi Benny,

So where is the schematic for the design.
Hi Walter ... my mate has chosen not to release the schematics at this moment in time.





The numbers my mate needs to run off a limited batch run for others are still a little short of the mark at the moment, so if you have a likely interest, pending suitable reviews of course, shot me a PM or say so here.


Cheers 


Russ


----------



## picree

For my HT setup the input in need of the greatest shadow enhancement is not the DVD player but it's the network OTA HD feeds (ABC, NBC, CBS). I've seen this discussed in numerous threads. Most prime time shows are unwatchable.


For that input (3 on the BarcoG 808) I'm using a VGA connector between the OTA HD box and the Barco. Anyone interested in a version of tse's card that has a VGA in/out? I use both VGA and RGBHV BNC inputs and would be interested in a card for both.


Picree


----------



## jtnfoley

So, tse, is the schematic posted herein up to date? I'm probably going to take on buildinig this circuit quite soon.


----------



## tse

Updated schematic, part I.


----------



## tse

Updated schematic, Part II.


Working on parts list. Might not happen until next week.


LT1213 opamp is harder to get than I though. More expensive, too. The circuit only needs a dual opamp with input offset voltage 1mV or less. Slew rate should be > 3V/uS. There should be one out there for less than $4.00.


----------



## tse

Gerber files.


*.gb0 = solder side

*.gb1 = component side

*.gb15 = top silkscreen/board outline

*.nc = nc drill drawing



The board is 3.4 X 8.2"


The board has been updated to revA.

 

AVS_GAM_DCR_revA.zip 187.927734375k . file


----------



## tse

Can I say this one more time? When watching widescreen DVDs the top and bottom of the screen is BLACK and I'm not reaching for the remote to turn up the brightness to see all the detail. Seeing only the letterbox picture on the screen is wild!


----------



## dustobub

Quote:

Originally Posted by *tse*
Can I say this one more time? When watching widescreen DVDs the top and bottom of the screen is BLACK and I'm not reaching for the remote to turn up the brightness to see all the detail. Seeing only the letterbox picture on the screen is wild!
No, please don't tell me how great it is. I know how much better my HTPC got when I adjusted the gamma, and I have been dying to have my other sources gamma adjusted. Thank you very much for your work on this project. As soon as the components are finalized I am building one.


Dustin


----------



## jtnfoley

tse (sorry to be a PITA) how about source files? The odds are very good I'll be incorporating your circuit into a larger project (which will also be opensourced and shared here) and I'd like to avoid redrawing.

Which application? I've got PCAD, Protel, PADS, TinyCAD, and another couple of freeware schematic capture apps from board makers.


----------



## GScott

Any chance that someone will be doing a batch of completed circuits? I would love to have gamma adjustment on my DVD and HDTV STB but I'm not sure I could build one of these.


----------



## jtnfoley

Quote:

Originally Posted by *GScott*
Any chance that someone will be doing a batch of completed circuits? I would love to have gamma adjustment on my DVD and HDTV STB but I'm not sure I could build one of these.
I'm quoting board fab right now... (only the bare board, not populated.) I'll reply again in a few minutes.


----------



## jtnfoley

Here ha go kids:

 

AVS-tse-GammaRevA-4pcbQuote.pdf 68.966796875k . file


----------



## jtnfoley

And the artwork converted to PDF. The gb1 file (in PDF format) is too large to upload.

The free quality checker at 4pcb.com found no showstopper issues (just a bunch of silkscreen line widths too short or too narrow.)

 

gb0.pdf 28.3046875k . file

 

gb15.pdf 28.0009765625k . file

 

nc.pdf 22.5771484375k . file


----------



## Tinman

Just read through this whole thread. I don't have much time these days so I missed this entirely. I also don't have the time to build one of these boards, but would certainly buy one. Please add me to a list of buyers if/when this becomes a finished product.


Marc


----------



## jtnfoley

Quote:

Originally Posted by *Tinman*
Just read through this whole thread. I don't have much time these days so I missed this entirely. I also don't have the time to build one of these boards, but would certainly buy one. Please add me to a list of buyers if/when this becomes a finished product.


Marc
Unfortunately, my production people won't touch anything with volumes this small (not even as a favor to me.)

Does anyone have a board stuffer in their pocket that'll do 10-20 boards?


----------



## picree

Count me in...buy or build, I don't care...I'd go in for a couple of bare boards or a couple of populated boards!


I would also go for a third board if it had VGA in/out instead of BNC. Anyone else interested in a VGA version of tse's card?


Picree


----------



## Person99

Quote:

Originally Posted by *GScott*
Any chance that someone will be doing a batch of completed circuits? I would love to have gamma adjustment on my DVD and HDTV STB but I'm not sure I could build one of these.
There seems to be much interest in having a completed box one can just buy. Given the cost of components, the completed box could probably be brought to market for somewhere between $200-$300. The question is, is it worth $100 or so profit on each unit for someone to take the time to actually productize it given the limited market? Any takers? It looks like you could sell 10-20 within the first few months.


Dave


----------



## Tinman

Quote:

Originally Posted by *jtnfoley*
Unfortunately, my production people won't touch anything with volumes this small (not even as a favor to me.)

Does anyone have a board stuffer in their pocket that'll do 10-20 boards?
Hey, I'll gladly take one in kit form. If I can get the board and parts, stuffing it is no problem. I might stuff a few for other people, depending on price... I have excellent soldering equipment and the skill to back it up. Look up Metcal gear.


Marc


----------



## Briands

Quote:

Originally Posted by *jtnfoley*
tse (sorry to be a PITA) how about source files? The odds are very good I'll be incorporating your circuit into a larger project (which will also be opensourced and shared here) and I'd like to avoid redrawing.

Which application? I've got PCAD, Protel, PADS, TinyCAD, and another couple of freeware schematic capture apps from board makers.
So what's the larger project??? Enquiring minds want to know???


----------



## benny

Quote:

Originally Posted by *GScott*
Any chance that someone will be doing a batch of completed circuits? I would love to have gamma adjustment on my DVD and HDTV STB but I'm not sure I could build one of these.
As I indicated in an earlier post , my mate can run off a limited batch of his design if a certain number can be reached. I've had a number of PM's from interested members but he's still a handful short of the minimum needed to warrant setting up the automation machinery.


May I suggest that if you have a strong interest in having a turnkey solution provided, that you shoot me a PM if you haven't already done so. It will make it easier for me to tally the numbers that's all.


Read my earlier posts to see the difference between TSE's design and the design I asked my mate to create.


I hope to have more details of CRO traces etc. next week.


Cheers all


Russ


----------



## jtnfoley

Quote:

Originally Posted by *Briands*
So what's the larger project??? Enquiring minds want to know???
Two sided, mostly SMT design (may require a four layer board) with a National Semiconductor LMH1251 transcoder (and it's mating line driver) and power on one side and the tse gamma circuit on the other.


I'm hoping to achieve three things with this effort...

1) Making the board small enough to be piggybacked on an RGB input card for the NEC ISS or Sony PC-1271/1272 switcher

2) Design it so that the transcoder parts OR the tse gamma parts don't need to be populated... just pick up the signal path after the fact by soldering the input and output COAX to a different set of pads.

3) Leaving enough board space on the transcoder side for later replacing the 1251 with the transcoder design being worked on by Walter (WTS,) Buen (don't know his real name) and Bill Blue.


Obviously, the small form factor board will allow packaging however the end user prefers and less obviously, new boards will have to be fabbed to incorporate the new WBBB transcoder as I don't have that schematic (yet.)

Unfortunately, my board stuffer down in Mexico won't touch anything (even on their "fast track" automation) unless we're talking about hundreds of boards.



As always, appologies to the [Boston accent]wicked smaht[/Boston accent] people here if I've overstepped my bounds by planning to combine the efforts of tse and the WTS/Beun/Bill Blue trinity.


----------



## Person99

Quote:

Originally Posted by *benny*
As I indicated in an earlier post , my mate can run off a limited batch of his design if a certain number can be reached. I've had a number of PM's from interested members but he's still a handful short of the minimum needed to warrant setting up the automation machinery.


May I suggest that if you have a strong interest in having a turnkey solution provided, that you shoot me a PM if you haven't already done so. It will make it easier for me to tally the numbers that's all.


Read my earlier posts to see the difference between TSE's design and the design I asked my mate to create.
It looks like you mate's design effects gamma across the entire range without even adjustments at various IRE points. Isn't this correct? If so, we need to "mess up" our gamma in the higher IRE ranges to get the shadow detail in the lower ranges with this type of solutions.


tse's solution only changes the gamma curve in the lower part of the curve to help shadow detail while leaving the rest of the curve uneffected if I understand correctly. This seems like the ideal solution.


tse's is a great solution for those with sources that allow some gamma adjustment but not fine tuning the lower end. My lumagen allows adjustment at 5 IRE points, but none below 20 IRE, thus tse's solution is just what the doctor ordered.


Dave


----------



## PAW

Dave


That's an interesting observation. I guess I didn't fully understand how these 2 designs differed. Thanks


----------



## techman707

Quote:

Originally Posted by *Person99*
It looks like you mate's design effects gamma across the entire range without even adjustments at various IRE points. Isn't this correct? If so, we need to "mess up" our gamma in the higher IRE ranges to get the shadow detail in the lower ranges with this type of solutions.


Dave
 That's wouldn't be called a gamma correction circuit......it's plain gain.  In a properly designed gamma correction circuit, while certain low level signals are amplified, high level signals are reduced (or clipped in some cases). In addition, it needs to be logarithmic.


----------



## Gordon Fraser

Person99: The current Lumagens with current firmware actually have 11 point gamma and you can set what points you want to adjust independantly, unlike the previous 20/30/50/80/100 five point version.


Gordon


----------



## Person99

Quote:

Originally Posted by *Gordon Fraser*
Person99: The current Lumagens with current firmware actually have 11 point gamma and you can set what points you want to adjust independantly, unlike the previous 20/30/50/80/100 five point version.


Gordon
Thanks for the correction. What are the points now, or relavent to this thread, what are the points in the low end?


Dave


----------



## Ericglo

Quote:

Originally Posted by *Person99*
It looks like you mate's design effects gamma across the entire range without even adjustments at various IRE points. Isn't this correct? If so, we need to "mess up" our gamma in the higher IRE ranges to get the shadow detail in the lower ranges with this type of solutions.


tse's solution only changes the gamma curve in the lower part of the curve to help shadow detail while leaving the rest of the curve uneffected if I understand correctly. This seems like the ideal solution.


tse's is a great solution for those with sources that allow some gamma adjustment but not fine tuning the lower end. My lumagen allows adjustment at 5 IRE points, but none below 20 IRE, thus tse's solution is just what the doctor ordered.


Dave
Dave,

This is what I understand to be the case as well. I believe it was tse's original intent to adjust the only the lowest points just enough to bring out the shadow detail and that was it. I am looking forward to seeing this solution and may have to make an unannounced visit. I definitely could have used it last night while watching Law and Order.


Eric


----------



## picree

Law & Order...obviously network HDTV through a STB. Does your STB output to your CRT through BNC's or VGA? I don't have the software, or know how to do a circuit board layout, or where to source it, blah, blah.....and was wondering if someone here was planning on making a board with VGA in/out instead of BNC's....


I would assume everything else would be the same on the board.


Anyone???


Picree


----------



## Ericglo

It is a VGA to BNC breakout cable.


Eric


----------



## benny

Judging by some correspondence I have been having here, there still appears to be some misunderstanding of the functionality of the design my mate created.


Just to re-iterate, it follows the standard gamma correction formula functionality which means it is as close to logarithmic in nature as you can get, with the added benefit of some additional correction at the very low end to enhance deep shadow detail. There is no clipping at the top end to compensate for anything. The design was chosen to portray the image as close to the way it was intended to be seen as possible without messing up the dynamics and balance.


If you are using a HTPC for gamma correction currently, as I am, and you have broad step adjustability via your video drivers, then this circuit will be beneficial due to its stepless adjustment between maximum and nil correction. If you are using a standalone DVD player, HDTV tuner etc. without ANY correction, then this type of circuit will be very helpful.


Cheers 


Russ


----------



## Tom.W

Hi Benny,

Can you expand on the added ability of additional correction at the very low end ?


----------



## mp20748

Quote:

Originally Posted by *benny*
Judging by some correspondence I have been having here, there still appears to be some misunderstanding of the functionality of the design my mate created.


Just to re-iterate, it follows the standard gamma correction formula functionality which means it is as close to logarithmic in nature as you can get, with the added benefit of some additional correction at the very low end to enhance deep shadow detail. There is no clipping at the top end to compensate for anything. The design was chosen to portray the image as close to the way it was intended to be seen as possible without messing up the dynamics and balance.


Cheers 


Russ
There's no misunderstanding of the functionality of your mates unit, look at the graph that you provided. Based on that graph, your mates unit effects overall gain, and would surely clip the high IRE's.


----------



## benny

Quote:

Originally Posted by *mp20748*
There's no misunderstanding of the functionality of your mates unit, look at the graph that you provided. Based on that graph, your mates unit effects overall gain, and would surely clip the high IRE's.
Hi Mike ...



As I mentioned in post #100 the circuit has an adjustable high upper limit which you need to set to your 100IRE voltage. This will ensure that there is no gain at 100IRE. The gain below 100IRE will be purely logarithmic, so NO, there is no clipping!


Having an adjustable output should have been an advantage I would have thought, similar in some way to the jumper setting you provide on the MP-1 mod fitted to my ATI card. I understand you provided that option so that some projectors which like a slightly higher signal will be accommodated.


Cheers 


Russ


----------



## tse

Quote:

Originally Posted by *jtnfoley*
tse (sorry to be a PITA) how about source files? The odds are very good I'll be incorporating your circuit into a larger project (which will also be opensourced and shared here) and I'd like to avoid redrawing.

Which application? I've got PCAD, Protel, PADS, TinyCAD, and another couple of freeware schematic capture apps from board makers.
The schematic is drawn with the demo version of Orcad. It is available for free download from their web site. It's pretty cool, capture, layout and even simulation. The PCB is made using PIA software from www.walherr.com . There is a demo available but you can't import or export gerber files without buying it (about $250). I'll upload any of the files that anyone wants. Just holler!


----------



## -Pjackso

Tse,


I know you've got your circuits working, but would you say they're "finished"?



And as other people have asked... Is anybody doing a powerbuy? If so, please speak up and we can start lining up the orders. (Tse, this is your baby - would you be interested?)


----------



## tse

The circuits look pretty good. I've been using the card for the last couple of weeks and can say that this is what CRT projectors have been missing since the beginning. They have always needed a boost down low and cutting back on the high level output doesn't hurt any. I don't want to get into the manufacturing of anything as I have a full time job and have no extra time for the hassles. I'll help anyone that asks, though.


----------



## picree

I can't do much to help here but maybe this will of some use. I've brought forward all info in the thread into one PowerPoint file. I don't have the component side layout as that was not uploaded and I don't have the "gerber" software. I copied all this from the other posts.


Layouts

Circuits-w/ updates

Parts lists


tse-dbl chk but I'm sure this has all the latest info.


If someone knows how to get one of these boards made please post (either bare or stuffed). I'll PM you. Looking for at least two.


Picree


Incorrect part # in original posted file (slide 6) has been updated to TL1213...not LT1213....

 

Gamma correction circuit.zip 302.349609375k . file


----------



## jtnfoley

Quote:

Originally Posted by *-Pjackso*
Tse,

I know you've got your circuits working, but would you say they're "finished"?

And as other people have asked... Is anybody doing a powerbuy? If so, please speak up and we can start lining up the orders. (Tse, this is your baby - would you be interested?)
If I can come up with a design for my combined transcoder / tse gamma circuit I'll certainly share the design just as tse has generously done.

My intent is to make the transcoder part optional, and design it for flexible input power (different regulators to work inside different switchers or even inside projectors, for the brave)


IF (great, big, hairy IF) the volume of committed parties (notice I did'nt say "interested parties") reaches a few hundred I may be able to have my board stuffer build boards. (My board stuffer has production capacity to stuff something like 130 million discreet components per month... they're not interested in small quantities.)

The boards would be delivered as boards... user-supplied packaging and I/O hardware would be mandated. I'm not interested in being a manufacturer either.


Anybody care to generate a wish list? I'm interested to learn what power options are required for internal use in PJs and switchers (external, boxed variants can obviously be fed by a wall wart) as well as BNC versus VGA I/O.


FWIW, the transcoder portion would be feature a RGBHV bypass even for those boards equipped with the chip.


----------



## garyfritz

Quote:

Originally Posted by *jtnfoley*
IF (great, big, hairy IF) the volume of committed parties (notice I did'nt say "interested parties") reaches a few hundred ...
Oh c'mon. Are there even a few hundred readers in this forum?? And what percentage of readers is going to commit to $300-500 or whatever your board will cost?


If it takes a few hundred to make it work, I'd say don't waste your time trying to get the stuffing done. Just publish the circuit and let interested parties stuff their own, or find someone to stuff it for them.


----------



## jtnfoley

Quote:

Originally Posted by *garyfritz*
Oh c'mon. Are there even a few hundred readers in this forum?? And what percentage of readers is going to commit to $300-500 or whatever your board will cost?


If it takes a few hundred to make it work, I'd say don't waste your time trying to get the stuffing done. Just publish the circuit and let interested parties stuff their own, or find someone to stuff it for them.
My offer was about 7/8 tounge-in-cheek. I tried to get my stuffer interested in a project (FOR WORK! The same company!) and they did'nt even no-quote it... volumes were just too small.


If I do lay out this design and release it, I assume the DIYers here would be MUCH more comfortable with thru-hole (over SMT.) This is (among) what I was trolling for in a "wish list."


How about it, group? Are we going to make tse's board as I had quoted a bunch of posts ago, or is there interest in a combined Xcoder/tse board?


----------



## Briands

Quote:

Originally Posted by *picree*
I can't do much to help here but maybe this will of some use. I've brought forward all info in the thread into one PowerPoint file. I don't have the component side layout as that was not uploaded and I don't have the "gerber" software. I copied all this from the other posts.


Layouts

Circuits-w/ updates

Parts lists


tse-dbl chk but I'm sure this has all the latest info.


If someone knows how to get one of these boards made please post (either bare or stuffed). I'll PM you. Looking for at least two.


Picree


Incorrect part # in original posted file (slide 6) has been updated to TL1213...not LT1213....
I get the following when I click your attachment:

Invalid Attachment specified. The post or the thread may have been moved into the archive.


Please try clicking HERE to read the archived post or thread. (If not found, it was removed.)


If you need further help, please notify the administrator.


----------



## picree

Quote:

Originally Posted by *garyfritz*
Oh c'mon. Are there even a few hundred readers in this forum?? And what percentage of readers is going to commit to $300-500 or whatever your board will cost?


If it takes a few hundred to make it work, I'd say don't waste your time trying to get the stuffing done. Just publish the circuit and let interested parties stuff their own, or find someone to stuff it for them.


Agreed...we may have 20-30 people interested at this point. If I could do this mod for ~$150 ish then I proceed. Stuff my own board?? OK. We just need a main contact that can work with someplace (4pcb.com?). Any takers?


I'm eager but, trust me...ya'll don't want me leading this...I'm gonna have to get a friend to show me how to mount all these parts just to get it together!


BTW-one of the boards says something about CW and CCW adjustments and "back porches". Do I need an oscilloscope to set this board up or can I just hook it up and make adjustments until it looks good???........see...I'm dangerous!


Picree


----------



## picree

Quote:

Originally Posted by *Briands*
I get the following when I click your attachment:

Invalid Attachment specified. The post or the thread may have been moved into the archive.


Please try clicking HERE to read the archived post or thread. (If not found, it was removed.)


If you need further help, please notify the administrator.


Try again Briands...I was updating the file just a moment ago.........


Picree


----------



## picree

I would just like tse's board, thru-hole...either stuffed or I can mount it. I'm looking for two (me and a neighbor)...or even three if anyone decides to set up a board w/ VGA I/O instead of BNC I/O.........


Picree


----------



## jtnfoley

Quote:

Originally Posted by *picree*
I would just like tse's board, thru-hole...either stuffed or I can mount it. I'm looking for two (me and a neighbor)...or even three if anyone decides to set up a board w/ VGA I/O instead of BNC I/O.........


Picree
That's the kind of input I'm soliciting... I'm hoping to create a generic board where people can chose to pupulate certain parts and make variations... certain traces would be bridged, for instance, to connect the VGA header.


Help me here guys, I'm trying for a "one for all" solution.


Barring waiting for my board, tse's latest design has been quoted at 4pcb.com (not currently set up for VGA inputs...) Look for a prior post from me.

Fell free to solicit a quantity and get them fabbed... I won't be offended!


----------



## picree

jtnfoley-What's the diff between Prototype and Production in the 4pcb quote? Just the counts? Do I read that quote right? 10 boards, 3 days, $240 total?


Give this a few days...if a senior member (who plays w/ boards and has done this before) doesn't step forward with an offer to place a bulk order w/ 4pcb then I would be willing...but really guys...I'm the nooby here and I would be out of my league. I can follow a circuit and solder parts on but I've never ordered a board before.


Picree


----------



## jtnfoley

Quote:

Originally Posted by *picree*
jtnfoley-What's the diff between Prototype and Production in the 4pcb quote? Just the counts? Do I read that quote right? 10 boards, 3 days, $240 total?


Give this a few days...if a senior member (who plays w/ boards and has done this before) doesn't step forward with an offer to place a bulk order w/ 4pcb then I would be willing...but really guys...I'm the nooby here and I would be out of my league. I can follow a circuit and solder parts on but I've never ordered a board before.


Picree
That's how I read it... $23.90 per board.

Check out their "specials" section... You can get (minimum) three boards for $33 each. This is a better price/unit than the smaller quantities in the proto from my quote.
https://www.33each.com/!33each1.asp 



The difference between Prototype and Production is summed up here:
https://www.4pcb.com/printed_circuit...production.htm


----------



## Atom

I would be interested in a couple of boards also.

Thanks

Andrew


----------



## jtnfoley

I just noticed that 4pcb also makes lasercut screens for applying solder paste... Hmmmmm Surface mount?


----------



## tse

That $33 ea for three boards is a good deal. They don't kill you with shipping and handling do they? I bought my boards two for $100 with shipping. No silkscreen. www.apcircuits.com charges $50 for set-up, $20 for shipping and about $16 per board.


If anyone had boards made with the previous files they will have to be sure and ground pin 5 of the dual opamps with a short jumper wire. Sorry, somehow I missed that with the RevX and RevA board artwork. That is fixed with the RevB stuff. Attached are schematics and PCB artwork with all updates and mistakes corrected.


Anyone is free to use this circuit as they please. Remember that if your video signal is already DC restored to zero volts you can use the far simpler original circuit.

 

AVS_GAM_DCR_RevB.zip 185.71875k . file

 

AVS_GAM_DCR_RevB_Schem.zip 20.482421875k . file


----------



## Chris Bigos

I'd take one or two boards if they around the $25 mark.


----------



## picree

How do I know if my video signal is "DC restored to zero volts"? I'm using a Crystal Image 2.0 scaler feeding a Barco 808G on the RGBHV input 5.


I see one adjustable component (resistor?) with some commentary about "back porch". What's back porch and do I need an oscilloscope to adjust it?


Any help is appreciated.


Picree


----------



## Briands

Count me in for a kit with a board and all of the parts. I would rather not have to chase down all of the componanats, but that would probably not be a deal breaker.


How is the design from a noise perspective? It's one more piece of equipment in the growing video chain between the source and the projector, so I think a little extra attention should be spend on making sure it does not introduce noise. Not that I know enough about it to really give any recomendations.


I know the numbers would be even lower, but in an effort to reduce connections in the video chain, I would be interested in the circuit added to an NEC ISS RGB output card. Petr made a transcoder input card for the ISS. I have an extra output card I could donate if someone wanted to tackle it.


----------



## Tinman

I'm up for a kit, or even an add-on kit for the ISS output card. In a pinch, I'll take just a board and a parts list. I sooo need this.


Marc


----------



## jtnfoley

When my ISS gets here I'll look into packaging constraints. A single card piggybacked inside the ISS on the output card would be cheaper than one for each RGB or VHS input, but as I need several transcoders I'm planning on making my own. Having the 'tse-gamma' circuit on each input has the benefit of tuning the circuit for each input (should this be required.)


If the packaging constrints are too tight, I may consider making the card the same width as an output card. It could slide into the rails beside the existing output card and be jumpered over (I want to avoid putting a big connector on one end...)


So Petr and Moome both have transcoding component input cards for the ISS? Why have'nt I found these yet?


----------



## Tinman

Quote:

Originally Posted by *jtnfoley*
So Petr and Moome both have transcoding component input cards for the ISS? Why have'nt I found these yet?
Oh, you know.... it requires obsessive checking of the CRT forum at least 5 times daily. You tend to trip across these things.... 


Marc


----------



## jtnfoley

This forum hasn't gotten me fired... yet. I do know they are watching my 'net traffic......... Fif you see that helicopter? The black one?


And those guys.... Those guys on the television on sundays.... I just know they're talking about me when they put their heads together like that!


----------



## picree

I may not be the most experienced in this thread but I can't wait for you guys to decide what to do. Just ordered 3 for $33 from 4pcb.com this afternoon. Best deal I saw.


tse-I may have a few questions about testing/setup and power supplies. I'll PM you if that's OK.


Picree


----------



## tse

Well, I'm back online after an unfortunate lightning event. I'll be happy to help in any way that I can.


----------



## Chris Bigos

Picree


Let me know if you have one spare that you'd post across the pond. $33 + postage?


Thanks


----------



## picree

Sure Chris...assuming we don't need that third one. We plan on making/using two. The third will be a spare if we fudge one of the two. It might be a long wait though. With kids, soccer, holidays pressing...it might take us a while to finish them...I plan on checking back here though with results whenever we do finish. I'm curious to see multiple opinions regarding the improvements.


Certainly though SOMEONE on this thread would go in for the deal on 4pcb.com? I mean 3 for 99 bucks? There's almost 5,000 views on this thread!


Picree


----------



## gn2

I hate to lumber into this delicately technical thread with a blunt observation, but there are likely tons of people out here who would love to have what this is, but don't fully understand WHAT it is !

Is this a device which goes between source and projector to give physical gamma control ??

If so, then I'm sure every crt projector owner would be interested.

I would, my buddy with a G90 and a Marquee would, another buddy with a few 9500LC's would be interested, but so far, every thing I've read in this thread has been pretty technical.

Where do I sign up for a little gamma box for $35. ?

I have a few NEC ISS switchers, if I could add something to that to provide gamma control, I would LOVE that.

I'm available with my several NEC ISS switchers for beta testing if anyone is making something...

Somebody post a picture of the thing, made up and connected.

A screen shot of its effect would be great too...


----------



## jtnfoley

Quote:

Originally Posted by *gn2*
I hate to lumber into this delicately technical thread with a blunt observation, but there are likely tons of people out here who would love to have what this is, but don't fully understand WHAT it is !

Is this a device which goes between source and projector to give physical gamma control ??

If so, then I'm sure every crt projector owner would be interested.

I would, my buddy with a G90 and a Marquee would, another buddy with a few 9500LC's would be interested, but so far, every thing I've read in this thread has been pretty technical.

Where do I sign up for a little gamma box for $35. ?

I have a few NEC ISS switchers, if I could add something to that to provide gamma control, I would LOVE that.

I'm available with my several NEC ISS switchers for beta testing if anyone is making something...

Somebody post a picture of the thing, made up and connected.

A screen shot of its effect would be great too...
Yes on the physical gamma correction observation. The folks with the G90s may not need this device as the recent model, super-high-end scalers have multipoint gamma.


The cost on the existing design is _not_ $35.00... the bare board is $33.00 and the components and asembly cost will probably at least triple that.

I've got access to a VERY HIGH-END manufacturing site that could stuff a board like this for a few dollars (plus parts cost) BUT the volumes on this will never be high enough for them to even consider this. I've still not seen any respondants here that know of some in-between sized shop that would consider making twenty or thirty of these.

I've got a friend-of-a-friend guy I'm keeping in my pocket who does small volume board stuffing in Michigan. If there is enough interest I may contact him.


I'm working on a smaller, likely SMT version which I intend to be a bit of a universally packagable card... it'll have HD15F _and_ through-hole (for soldering coax) inputs and outputs and at least two power inputs. VGA connectors and power regulators would be optional, depending on whether the installation requires them, and it's my intention to make the card piggyback on an ISS input card, or match the width of the ISS rails so it can sit next to an ISS input card.

I'm not feeling ambitious enough to make this card fit an ISS exactly (with the correct header connector on the back and filler/input plate on the front... Besides, I want this thing to work within a Sony PC-127x switcher also.


And, since I desperately need a few good transcoders, I intend to make this theoretical uber-tse card have that input option, also. Very likely I'll have jumpers or solderstraps to bypass the transcoder-and-linedriver section


Right now I'm evaluating a low-to-mid cost schematic capture program that the average hobbyist in this community can afford (Eagle by CADSoft) hoping that the maintainence of this design will be picked up by others. I, of course, will be releasing everything just as tse has released his brilliant work.

In the way of learning Eagle, I'm redrawing tse's original 2 layer thru-hole design with HD15F VGA connectors. I should be able to push this out this week or next.


As for an ETA on the uber-tse board, I'd estimate weeks at best. There's a lot of conflict for my time lately.


----------



## Chris Bigos

Quote:

Originally Posted by *picree*
Sure Chris...assuming we don't need that third one.
Thanks - only if you find you have one spare, of course. No rush, I wouldn't get around to it for a while anyway.


----------



## tse

Quote:

Originally Posted by *picree*
I may not be the most experienced in this thread but I can't wait for you guys to decide what to do. Just ordered 3 for $33 from 4pcb.com this afternoon. Best deal I saw.


tse-I may have a few questions about testing/setup and power supplies. I'll PM you if that's OK.


Picree
Picree,


Which revision board did you order? The Rev B artwork is good to go. Rev A will require a jumper to ground pin 5 of the LT1213s. The first Rev will need the Rev A jumpers as well as a jumper to ground pin 1 of the LM311.


Any questions happily answered.


tse


----------



## tse

Quote:

Originally Posted by *jtnfoley*
tse (sorry to be a PITA) how about source files? The odds are very good I'll be incorporating your circuit into a larger project (which will also be opensourced and shared here) and I'd like to avoid redrawing.

Which application? I've got PCAD, Protel, PADS, TinyCAD, and another couple of freeware schematic capture apps from board makers.


The schematic capture is with Orcad. They have a demo available on their web site.


The PCB layout is PIA software from www.waldherr.com . There is a demo available there, but you can't do much more than view and print the files.

 

AVS_GAM_DCR_SCH_RevB.zip 23.89453125k . file

 

AVS_GAM_DCR_PCB_RevB.zip 18.21484375k . file


----------



## picree

I used the Rev B. artwork. Thanks.


I'm drawing up a set of questions but will try to do it all in one shot to make it easier for you. Mostly about the IC selections.


Picree


----------



## picree

tse-In doing a take-off I noticed that the schematics only have a total of 5 100 ohm resistors but the silkscreen shows 9.....did I miss something?


picree


----------



## tse

Nope, I did. Good thing you guys are around to keep me straight. Correct schematics attached.


----------



## picree

Thank you sir. Everything else seems to add up...143 parts on the board and 143 parts on the schematics.


----------



## tse

Parts list with catalog numbers. Everything ending with -nd is from Digi-Key. All others are Newark. Some searching around could probably save some money but I used the least expensive parts that were easy to find. The LT1213s are terribly expensive and I am looking for cheaper parts.

 

AVS_GAM_DCR_PList_RevB.txt 2.34375k . file


----------



## picree

tse-OMG! 


Is it possible for you to make this ANY easier??? I was in the process of running these down and making a similar list. This is greatly appreciated! Hopefully, those in this thread will find this easy enough that several of these will be made up and tested with different setups!


----------



## Person99

Quote:

Originally Posted by *picree*
tse-OMG! 


Is it possible for you to make this ANY easier???
Someone build the damn box and sell it to us lazy folk!


Dave


----------



## Belcherwm

Quote:

Originally Posted by *Person99*
Someone build the damn box and sell it to us lazy folk!


Dave


----------



## PAW

Quote:

Originally Posted by *Person99*
Someone build the damn box and sell it to us lazy folk!


Dave
Or those of us without the skills to build one.


----------



## picree

tse-Are C3, C4, and C5 on the Video circuit now 22 uF instead of 10 uF?


----------



## picree

According to a DigiKey tech a couple of alternatives for the LT1213's might be:


DigiKey part no 296-10464-5-ND $2.13 ea


or


DigiKey part no AD823AN-ND $5.00 ea


I have no idea if these meet the specs. tse-any thoughts?


----------



## benny

Quote:

Originally Posted by *Person99*
Someone build the damn box and sell it to us lazy folk!


Dave
For the non-DIY fraternity keep an eye on this thread:

http://www.avsforum.com/avs-vb/showthread.php?t=588046 


Cheers 


Russ


----------



## picree

FYI to the group-this DIY option from tse prices out almost right at $100 not including any BNC jumpers and any required power supply. I sourced all parts as listed by tse above (DigiKey mostly and Newark). The boards came from 4pcb.com...the 3 for $99 option.


Cost breakdown-round #s:


Circuit board $40

The LT1213 op-amps $20

The BNC connectors $15

Everything else $25


----------



## PAW

tse

Would you have a gamma curve graph you could post? Even a hand drawn one is fine by me. I'm interested it comparing it to Benny's mate's design. Is this a black box design? Meaning there's input and output but no on switch, no adjustment knob, etc.? Are there any internal adjustment pots?


picree

Thanks for the price break down. For the BJC jumpers, I assume you mean the short BNC cables needed to hook this thing up. Also, does this include the cost of a case? Now I just need to find me an EE student to build one.


----------



## picree

PAW-


BNC jumpers-yes...the four short cables needed to go between this board and the CRT input or scaler output depending upon which end its connected to.


The cost is without a case or the jumpers or a power supply.


----------



## Briands

Any comment on S/N for the unit... Like I said previosly, I like the idea of gamma correction, but I'm not excited about putting something in the signal chain that is going to introduce noise.


----------



## tse

The caps were originally going to be 10uF but I ran across some 22uF for cheap so I used those. Their value isn't critical and either would work.


The 10uF NP cap used at the input is more critical and some changing of loop compensation might be needed if changed in value.


I haven't tried these but they look good from a spec sheet point of view. MC33077POS-ND for $1.30 ea from Digi-Key. A possible sub for the expensive LT1213s.


----------



## tse




PAW said:


> tse
> 
> Would you have a gamma curve graph you could post? Even a hand drawn one is fine by me. I'm interested it comparing it to Benny's mate's design. Is this a black box design? Meaning there's input and output but no on switch, no adjustment knob, etc.? Are there any internal adjustment pots?
> 
> 
> 
> Attached are curves with two different resistor values in the circuit. There could be pots but I don't think it would be easy to get all three colors to track. By changing fixed 1% resistors in each circuit the tracking will be good. A wide range of responces are possible but it would require changing resitor values.
> 
> 
> The R=2.4K curve looks pretty good to me. The other would have the dark details look like you were using night vision equipment.


----------



## Tinman

OK... soooo.... are we going to be able to get the PCB?? What's the plan on that?


Marc


----------



## jtnfoley

Quote:

Originally Posted by *Tinman*
OK... soooo.... are we going to be able to get the PCB?? What's the plan on that?


Marc
I believe tse has done his part in engineering, debugging, and testing this circuit. I'm in the process of creating a smaller board with VGA HD15F inputs and outputs and incorporating an optional transcoder. (My effort will take weeks at my current pace.)


The community (subscribers to this thread, at least) should arrange a bulk buy and order the boards in quantity.




Picree, care to answer the call?


----------



## picree

Sorry, I already ordered a set of three bds from 4pcb.com last wk. I'm using two (one BNC and one I hope to wire up to VGA) and my neighbor agreed to take one. With shipping they were $38/bd.


Getting three together was easy enough. And the diff in $ wasn't too bad. I think the next price break was something like QTY 10 (was that about $23/bd?)...in case I did something wrong I really didn't want to risk messing up ten (I've never ordered from 4PCB before)....


Uploading the Rev B files posted above to 4pcb.com was very easy. A larger bulk order of 10-20 bds should be by someone with a little more experience than me just in case anything comes up. 


If someone ran out ALL the cost savings ideas here (bulk buy, cheaper op-amps, VGA instead of BNC) the cost would be about $60/bd. To me that's close to $100..and I can start on it NOW!..although I'm not rich...I'm impatient!


----------



## jtnfoley

There's another inexpensive op-amp option, but I'm too EE-ignorant to know whether it's appropriate for this application. A 3 channel package by National Semiconductor that's marketed as an RGB buffer (the recommended mate to their LMH1251MT transcoder that I hope to use...)
http://www.national.com/pf/LM/LMH6739.html 


Related question for tse and the rest of the "real" EE's here... Since the LMH1251MT transcoder can't source much current, National recomends the 6739 buffer. But, it requires a different power supply (10V nominal) than the 1251 or anything in the tse gamma circuit.

Is the tse gamma circuit sufficiently high in impedence to keep the 1251 happy? If I'm reading the spec right, the 1251 chip can only source three mA (per color and per sync pin, apparently.)


----------



## PAW

tse and Benny

I'm trying to compare you gamma curve graphs (Benny's is in post #100 of this thread) and I'm confused. Unfortunately, I don't profess to being anything close to an EE. 


tse

- What should the horizontal axis's units of measurement be?

- Why are there two units of measure on the vertical axis?

- In the actual graphed lines, what do the horizontal sections mean?


Benny

- What are the horizontal and vertical units of measurement?

- This is not graph related but I know the gamma correction is adjustable. Is it a single adjustment or an adjustment for each color (RGB)?


tse and Benny

tse's 2.4K graph looks pretty similar to Benny's red line in his graph. The "hump" in Benny's red line looks to be a little thicker and higher up the graph. I assume this means that Benny's box produces more gamma correction and higher up in the IRE range? I also noticed that tse correction curve tapers off quicker. I guess this means less correction higher in the IRE range? Benny I understand a secondary benefit of your box is to boost the entire range. To help PJs that want a slightly stronger signal.


Thanks for entertaining my questions.


----------



## Person99

Benny's adjust the whole gamma curve. The same as if you have gamma in a DVD player and adjust it +1, +2, etc. tse's is designed to address a very specific CRT "problem". tse is remapping the gamma primarily in the lower IRE such that a black out screen can be absolutely pitch black and you can still have excellent shadow detail in the lower IRE range. He only effects the upper portion of the curve for a natural transition.


At least, that's my take. 


Dave


----------



## tse

Quote:

Originally Posted by *Person99*
Benny's adjust the whole gamma curve. The same as if you have gamma in a DVD player and adjust it +1, +2, etc. tse's is designed to address a very specific CRT "problem". tse is remapping the gamma primarily in the lower IRE such that a black out screen can be absolutely pitch black and you can still have excellent shadow detail in the lower IRE range. He only effects the upper portion of the curve for a natural transition.


At least, that's my take. 


Dave
You have it exactly right. I am only interested in boosting the dark image detail to the point where you can set your brightness control for black output with black input and still see detail in the shadow areas.


----------



## tse

Gamma circuit response in IRE units. Input vs output. I'm trying for the same output level as input, so gain = 1. The picture shows one line of a 16 step stairstep pattern. Darkest bar on the left, brightest bar to the right.

 

AVS_IRE.zip 7.8466796875k . file


----------



## PAW

OK! That's clearer now. Thanks tse!


----------



## jtnfoley

Another board source:

http://www.custompcb.com/ 


I've not looked at board sizes and "real" price comparisons, but this source may bridge the price/quantity gap between 4PDB's "prototype" and "production" rates.


----------



## tse

I sent the files to CustomPCB for a quote. Will be interesting to see what they come up with as they are located in Malaysia.


----------



## jtnfoley

Quote:

Originally Posted by *tse*
I sent the files to CustomPCB for a quote. Will be interesting to see what they come up with as they are located in Malaysia.
Send them a schematic in Eagle, OrCAD, or Protel99 and they'll do the board layout for you... for FIFTEEN BUCKS AN HOUR! 

As my dearly departed Dad used to say... "That's like a sore dickey... Can't hardly beat it."


----------



## tse

Quote:

Originally Posted by *jtnfoley*
There's another inexpensive op-amp option, but I'm too EE-ignorant to know whether it's appropriate for this application. A 3 channel package by National Semiconductor that's marketed as an RGB buffer (the recommended mate to their LMH1251MT transcoder that I hope to use...)
http://www.national.com/pf/LM/LMH6739.html 


Related question for tse and the rest of the "real" EE's here... Since the LMH1251MT transcoder can't source much current, National recomends the 6739 buffer. But, it requires a different power supply (10V nominal) than the 1251 or anything in the tse gamma circuit.

Is the tse gamma circuit sufficiently high in impedence to keep the 1251 happy? If I'm reading the spec right, the 1251 chip can only source three mA (per color and per sync pin, apparently.)
The LMH6739 is essentially three HFA1100s in one package. The price at $5 is good and the shutdown function is cool. It could be used in the gamma circuit but the resistor values around the 1100s would have to change a little. If you decide to use it I can recalculate the resistors for you. It does make the PCB layout more difficult, though.


The LMH1251 could drive the gamma circuit if you remove the 75 ohm input resistors. Without that resistor the input resistance of the circuit is about 20K so there would be no problem. The sync outputs need to be buffered if you are driving 75 ohm coax. The chip ain't got the oomph to drive that low of an impedance. Their typical application circuit showing diodes to ground after the coupling caps isn't needed for the gamma circuit. Just connect the output directly to the input cap on the gamma circuit.


----------



## buttsplice

tse, how did you derive the gamma curve that you're using? I'm driving my pj directly with an htpc via breakout cable so I don't need a hardware solution at the moment but I do need shadow boost so I'm trying to implement this in software using a little color calibration utility that stores each level as a decimal number in a text file. Did you figure out the curve through trial and error or is there a method to your madness?


----------



## tse

Well, I knew that I wanted a boost in the dark (low IRE) area so a few opamp circuit calculations and some spice simulation time did it. Actually, I've worked on this and similar circuits for light valve projectors many times.


----------



## tse

Quote:

Originally Posted by *tse*
I sent the files to CustomPCB for a quote. Will be interesting to see what they come up with as they are located in Malaysia.


If I shrink the length of the board from 8.2" to 8.0", six boards would be $93. That's $81 for the PCBs and $12 for shipping. No silkscreen or soldermask.


----------



## Briands

Whoever is looking at putting an order together, count me in for one.


----------



## tse

A little update. Attached are Rev C board files that are 8" long instead of the original 8.2"


I tried TLC277CP opamps in place of the LT1213s and they work fine. They are less than $2.00 each which is alot better than the $6.00 the 1213s cost. Based on this I am comfortable saying that MC33077 in the DIP package would work also. They are $1.30 from Digi-Key.

 

AVS_GAM_DCR_RevC.zip 188.80078125k . file


----------



## picree

Sigh..... 


Digikey ships a package with 384 parts in it...EVERY part's correct. Great! What a company!


4pcb.com ships a package with only three parts in it. Only problem is...THEY'RE NOT MINE! They belong to some guy in West Lafayette Indiana!  SHEESH! I'm trying to keep in mind that this is only a hobby but boy am I frosted. 


Do they really think the free T-shirt and free pack of popcorn is going to make me feel better about getting the wrong board??


Let's see what kind of company they REALLY are.......


Picree


----------



## tse

Yikes! That is a bummer. I'm sure they'll make it right. Make them give you a discount coupon for your next board.


Digi-Key is an excellant company. I wish it was publically traded on the stock market. I'd buy their stock.


----------



## picree

OK-4pcb.com fixed it right away as best as they could. I would buy from them again and would recommend them. They found the lost boards and had them here the NEXT day! Great!


tse-I've got a question about the board. The current feedback amplifier on the blue channel has pin one grounded to the ground plane (the HFA110). The amplifiers on the green and red channels do not have pin one grounded. The board picture you posted earlier also showed no ground for pin one.


The datasheet for the HFA1100 says pin 1 is uncommitted/no connection so it probably doesn't matter but I wanted to check.


----------



## tse

Space, the final frontier...........


No, pin one of the HFA1100 shouldn't be grounded. It might not matter but I'd take an Exacto knife and trim the runs from the pin.


Sorry 'bout that.


----------



## picree

Just finished a board. Hooked it up to my neighbors BG1209 and I have to say it looks AWESOME! He has a color meter so we're going to go through a redo on the grayscale but first impressions are beautiful! Upping the NTSC signal gain and letting the Barco settle on a lower black level almost makes the image look 3-D...certainly on some of the CGI scenes in Fifth Element! 


I can't wait to work up another one for the HDTV input on my 808. That's the one that needs mucho gain enhancement!


Thanks tse. This has really been a fun project!   


My friend was wondering about the power supplies on the board and if he needed to be worried about power feeding back into his Lumagen scaler? My guess is no but thought I'd ask, any issues there?


tse-Can I use two isolated power supplies to power two boards instead of four separate ones? Just chain the leads together?


Oh, BTW...total cost has been around $140/bd. (that's bd, parts, RG-6 cables, and power supplies, but excluding a box which I have yet to find). And act fast, partsexpress.com has power supplies for $1.40 ea. plus shipping!!!! 


picree


----------



## tse

Cool! I'm glad you got everything going. Good job for getting it right the first time around.


Your friend has little to worry about. There are coupling caps between any circuitry and the video source. Not likely that they will fail.


If your power supplies can handle the power requirements there should be no problem connecting two boards together. After all, they are connected together through the video cables (ground).


I've had very good performance with DVD. The shadow details are much improved. Off the air HDTV is all over the place as far as black crushing is concerned. One show looks great, a commercial comes on and it looks like they used linear video with no gamma correction and the blacks are in the dirt, then another commercial comes on and it's washed out like the brightness is maxed out. The better quality channels look the best though.


An aluminum box made by Hammond Manufacturing 9' x 5" x 2" 1444-14

Cover for box 1434-14


Digi-Key has 'em.


----------



## picree

As I mentioned before you made it VERY easy to get it right! Although, installing the polar caps on the negative DC circuit backwards almost caught us! Never seen that.


This isn't a very scientific analysis but it really makes the entire signal more vivid. It jumps out at you without being too much of a strain on your eyes. I suppose that's from the better blacks. I've done a bunch of tuning and a few mods on the 808 (Avia setup, phosphor masking, color gels) and I would have to say this ranks as probably the best upgrade so far!


We're going to take a look at my friends color meter setup before and after to see the actual improvements. If we can figure out all the ins/outs of the software I may be able to post relevent results here. I'll see if he's up for it.


My fervent hope for the HDTV is to get the HD sports broadcasts, and some of those ever-so-dark cop shows dialed in better. Right now the evening HD lineup is unwatchable unless I crank up the brightness...then of course it's all washed out. Eventually, when commercials and everything are HD it hopefully will play better. HD won't be HD until it's ALL HD and dialed in.


Thanks for the box # tse!


----------



## tse

A little update for anyone that has built or is going to build this circuit.


The original development was done using a DVD player running wide screen format with RGBHV output. Since then I've been running off the air HDTV with the image zoomed out to fill the 4:3 screen that my projector normally runs.


Some TV stations send some really "hot" video that is more like 0.8Vpp than the typical 0.7Vpp stuff, particularly during commercials. This "hot" video can exceed the range of the DC restore circuit.


Add a 220K 1/8W resistor from pin7 (+5V) to pin3 (+ input) of the HFA1100s. Keep the resistor close (

This change is appropriate for any reasonable level video input.


----------



## Tinman

Is anyone going to offer the sale of the PCB itself?


Marc


----------



## darinp2

Has anybody considered asking Lumagen to put this kind of capability into one of their scalers? They already have some gamma adjustments available, but I don't believe they have what you need here at the moment and there is probably a reasonable chance that they could add it.


--Darin


----------



## picree

Quote:

Originally Posted by *tse*
A little update for anyone that has built or is going to build this circuit.


The original development was done using a DVD player running wide screen format with RGBHV output. Since then I've been running off the air HDTV with the image zoomed out to fill the 4:3 screen that my projector normally runs.


Some TV stations send some really "hot" video that is more like 0.8Vpp than the typical 0.7Vpp stuff, particularly during commercials. This "hot" video can exceed the range of the DC restore circuit.


Add a 220K 1/8W resistor from pin7 (+5V) to pin3 (+ input) of the HFA1100s. Keep the resistor close (

This change is appropriate for any reasonable level video input.
What is the result of exceeding the range of the DC restore circuit? Does the image blank out?


Could I just go on the back of the circuit board and solder on the resistor leaving all other connections as is?


And lastly, when you say "The change is appropriate for any reasonable level of video input", do you mean that this mod can be done on any and all boards with any and all inputs without negative consequences?


----------



## tse

When the DC restore runs out of range the black level that should be clamped at zero volts goes slightly negative and the peak to peak output level increases one or two tenths of a volt more than the input level. I didn't see anything wrong in the projected picture, just noticed it on the scope.


It won't hurt anything to make this change even if you are only watching widescreen sources.


----------



## picree

tse-I can't say enough about how much better the imaging looks after gamma correction. We watched a couple of movies that had scene transitions that snapped to black for a few seconds and it was SOO cool to see it REALLY black. I couldn't even discern the 1.3 gain screen from the black masking border.   Tomb Raider has a scene of the night sky and oh boy did it look awesome!


You said previously that you only had to bring down the brightness. Without the board, I was running 35/75 on the brightness/contrast. With the board in, and after a quick Avia check I ended up with 27/57.  And at a lower brightness the other colors are a bit more vivid. (We decided it was time to redo the color set up so maybe we got a little image improvement from that but I think it's mostly coming from the better shadow detail.)


Anybody else finish this board and have any comments?


----------



## Semisentient

Well, I have the board and all I can say it rocks! I have a Momitsu DX880 hooked up to a Sony 1292Q. The Momitsu is known to have a weak output and not have a good gamma curve for CRT projectors. To help with these problems I was using an Extron 109E to boost the signal. It did help with lower level detail a bit and pumped the signall up enough to make the picture very bright. Problems with this was I could actually push the 1292 into blooming and whites got crushed.


Enter tse's circuit...


The difference in low level detail is huge. Scenes that once looked murky with faces half cast in shadow are now detailed. The over all balance of the picture is much improved. Scenes like the caves of Moria at the end of Fellowship of the Ring look much much better. The difference this circuit makes is not small.


I have one channel on my projector setup for use without the Extron. I am now using that channel with the contrast and brightness turned down from where I had it.


If you don't have gamma control from your source or in your projector I would say you need this circuit!


James


----------



## jtnfoley

I'm very near to providing a VGA/HD15 input version for review. Hopefully I'll be able to work on it some more soon. Then on to incorporate transcoder functionality.


----------



## Ericglo

James and picree,

I guess you two are the first two guinea pigs. Is it really a night and day difference? If so,

then this is a very significant development. I was hoping it would be as much.


Ericglo


----------



## Semisentient

Quote:

Originally Posted by *Ericglo*
James and picree,

I guess you two are the first two guinea pigs. Is it really a night and day difference? If so,

then this is a very significant development. I was hoping it would be as much.


Ericglo
For certain scenes I would say the difference is night and day. I am going by memory, but scenes I wasn't satisfied with before are fine now. Right now it would be a bit hard for me to switch back and forth for an A/B comparison, but maybe soon. If I do I will try and take pictures...



James


----------



## garyfritz

Finally found my soldering pen (it got buried in my HT closet ) and I hope to sit down and solder up my circuit soon. I'm not used to working on circuitry this fine. Is self-fluxing rosin solder OK, or should I apply flux first before soldering?


----------



## jtnfoley

Quote:

Originally Posted by *garyfritz*
Is self-fluxing rosin solder OK, or should I apply flux first before soldering?
Use a relatively small diameter and you'll be fine. Google for a technique tutorial, but (on thru-hole parts) I generally try to heat the pad and pin simultaneously, without using a great deal of force (the copper is glued to the circuit board, and too much heat and force can move and break a pad away from it's trace.)


----------



## garyfritz

Sounds straightforward enough. I've been wrangling a soldering iron since I got my EE / CS degree 25 years ago, but I've spent all my time since then doing computer stuff instead of electronics. Circuits have gotten a lot smaller since then.


----------



## jtnfoley

I believe everything in this thread has been thru-hole... you should'nt have any trouble. The board I'm working on may require SMT, which I am loathe to do but packaging requirements might mandate. At least I'll try to use 1206 parts wherever possible


----------



## picree

Quote:

Originally Posted by *Ericglo*
James and picree,

I guess you two are the first two guinea pigs. Is it really a night and day difference? If so,

then this is a very significant development. I was hoping it would be as much.


Ericglo
I'm finishing up my second board tonight for the OTA HDTV input. I finally can have total blacks between scenes. The credits at the end of the movies don't streak off the right of the screen. With blacker blacks the colors in the scenes look more vivid. I was able to lower my brightness from 35 to 27 and still get the same shadow detail. That really enhanced the colors. I can't wait to see what HD looks like! 


Anyone running their HT off a PC can do the same thing this board does with gamma correction. But, if you don't have that setup then IMHO this upgrade is definitely worth it. The only way to find out is to try it for yourself. For me-it's great!


Follow this thread closely. There are a handful of tiny mods after the Rev B board came out. Good luck.


----------



## Chris Bigos

Quote:

Originally Posted by *picree*
Sure Chris...assuming we don't need that third one. We plan on making/using two. The third will be a spare if we fudge one of the two.
That's great news - you've worked pretty quickly. Sounds like it was well worth it.


So - d'ya make any fudge?


----------



## Belcherwm

I'm not talented enough to make one of these. If anybody is interested in selling one please keep me in mind. This would solve, what I would consider, the the biggest deficiency in my setup.


----------



## misohorny

I was just downloading this thread for a leisurely read when I noticed that Firefox abbreviated the title to "Shadow detail/gamma enhancement for the anal" in the save window.


Fair enough. 



John


----------



## picree

Chris-I pm'd you........


misohorny-my wife agrees!


----------



## Gaber

Quote:

Originally Posted by *picree*
Follow this thread closely. There are a handful of tiny mods after the Rev B board came out. Good luck. 
Does the Rev C version address all these tiny mods or are there others in addition?


Where in the signal chain are you attaching these boards?


I have an NEC 6010 switcher in which I would like to attach this. Does anyone know if the proper power supply voltage exists in this switcher? Also, if I do put it in the switcher, can it drive a 25 ft cable run?


Finally, I might be willing to produce a small number of these if there is a significant price break.


Gabe


----------



## picree

Quote:

Originally Posted by *Gaber*
Does the Rev C version address all these tiny mods or are there others in addition?


Where in the signal chain are you attaching these boards?


I have an NEC 6010 switcher in which I would like to attach this. Does anyone know if the proper power supply voltage exists in this switcher? Also, if I do put it in the switcher, can it drive a 25 ft cable run?


Finally, I might be willing to produce a small number of these if there is a significant price break.


Gabe
The rev C board had one of the HFA1110's number one pins grounded when it shouldn't have. Scrape it off. The parts list that tse posted substituted 22 uF caps for the 10 uF caps on the schematics. An additional resistor was added to the HFA's. The op amps were changed from the LT1213's to a cheaper version. I just suggest following the thread in order and pay attention to tse's posts.


I put this board on top of the projector with 16" jumpers into the RGBHV input because it was out of the way. Just make sure to put the power supplies up in the rafters. Laying on the top of the projector can mess with the CRT's.


Don't know about your switcher. Building less than ten probably wouldn't result in much of a price break.


----------



## jtnfoley

Quote:

Originally Posted by *Gaber*
Does the Rev C version address all these tiny mods or are there others in addition?


Where in the signal chain are you attaching these boards?


I have an NEC 6010 switcher in which I would like to attach this. Does anyone know if the proper power supply voltage exists in this switcher? Also, if I do put it in the switcher, can it drive a 25 ft cable run?


Finally, I might be willing to produce a small number of these if there is a significant price break.


Gabe
The version I hope to release to review soon will be packaged to fit inside of an NEC ISS 6010 (small enough for packaging du'jour...) I don't know whether the tse Rev C version will fit. It is my intention to "daughter" the board onto an RGB or VGA input in my ISS.

The ISS 6010 provides +15VDC and -15VDC as well as +5VDC (and ground.)


----------



## Z-Photo

OK,


Just got done reading the entire thread. Great job Tse..


ummmmm

SIGN ME UP...... 


Let me see if Cary want in on this.....since I can not do the soldering/EE stuff - But I do have money (and pictures)....... 


Pete


----------



## jtnfoley

Quote:

Originally Posted by *jtnfoley*
The version I hope to release to review soon will be packaged to fit inside of an NEC ISS 6010 (small enough for packaging du'jour...) I don't know whether the tse Rev C version will fit. It is my intention to "daughter" the board onto an RGB or VGA input in my ISS.

The ISS 6010 provides +15VDC and -15VDC as well as +5VDC (and ground.)
Sorry to quote myself, but i wanted this reply to reach everyone with an email notice (which an --Edit: won't do...)


The Rev C tse design is, I believe, 8 inches long and 3.2 inches wide. The NEC input cards are 8 5/8" x 3 15/16".

Therefor, you could standoff a tse rev C board to a throw-away piece of breadboard, and pick up +15, -15, and ground from the DIN64 connector on an adjacent RGB input board, and RGBHV input and output from the same card by isolating the inputs at the BNCs.

I don't have a RGBHV board myself, so I don't know whether there is a "safe" place to pick up standoffs directly. This, and that the tse board is very close in size to an ISS input card, is why I'm recommending putting one in an adjascent slot.


And, no I don't plan to design an NEC-ISS specific input card. The DIN64 connector is cheap enougn (less than four bucks from digikey) but there is a bunch more logic on the ISS input boards (possibly related to RGB gain) that I don't have time to reverse.


FWIW, the filler plates on my ISS 6010 are actually board mounting plates with screw ears, so you could create a board set for input and still maintain a clean look.


Don't know how readable this'll be:


----------



## jtnfoley

Bump and Paste...


Back by popular demand...Get your boards twice as fast at no additional cost.

Order now and get a 2-week delivery on your printed circuit boards at a 4-week

price or a 1-week turn at a 2-week price.


For details Please visit www.4pcb.com 


You've been asking for it...now you've got it!


P.S. Don't forget...we are also offering 1-day Free expedite on Protos. Call me for details.


----------



## dustobub

Anybody want to build me one? What is the total cost to build one myself? Thanks.


Dustin


----------



## Person99

Quote:

Originally Posted by *dustobub*
Anybody want to build me one? What is the total cost to build one myself? Thanks.


Dustin
We've been trying to get someone to build these for us lazy folks for awhile. Nobody wants to do it!


Dave


----------



## gn2

Put me on the lazy list, if any one wants to build them, I'll buy two at least, maybe three or four.


----------



## WTS

Hi gn2,


Hmmm, cables inexchange for building boards, could work, PM me.


----------



## picree

dustobub-read the thread...cost per board to build it yourself is $150.


Build the board by hand?...too much work...even for $300.


Build them in a lot with automation?...probably need 25-50 to make a run...so one of you guys needs to start taking orders......get busy...this ain't no charity forum.


It's a good CRT projector mod. It works and looks great.


----------



## PAW

picree

How long did it take to build the board and what was the total time to complete the project (stuff it in a box, etc.)? There might be some poor starving EE students near me who would be happy with $25 (tax free) an hour.


----------



## buttsplice

Ha, I can tell you that a poor starving EE student will accept a LOT less than 25 smackers an hour to populate circuit boards! Most EE's here will be lucky to make that much at their first job after graduation! 


I work at a small design/production place but even as small as it is I don't know if it'd be worth getting the machines set up to run 20 boards, especially since tse's layout is through-hole and would have to be run through the pick'n'place then through the wave solder machine. It might be reasonable if it was all SMT. Most of our runs are in the thousands of units but I suppose if there's enough profit on each board then it might be worth it. Does anybody have a BOM like listed earlier except with prices on each in a spreadsheet with a total cost? I could pitch it to the boss if I had all the information, though I definitely don't have the money to front an operation like this, as a poor starving EE student


----------



## Briands

What about a group buy on a kit- just the final design board and a parts list (with item numbers) to order from digikey etc? I would not mind trying this myself (plus I could find help if necessary). I just want to make sure the design is final and that I could get the board without having to order a gross.


----------



## RGBHV

Put my vote in for a Kit too!


----------



## Person99

Quote:

Originally Posted by *RGBHV*
Put my vote in for a Kit too! 
I guess lazy me can put a kit together, so if we can't get a finished one, I'd go for a kit if someone whats to put them together.


Dave


----------



## Tom.W

This could be a good side business for Moome . Has anyone asked him if he is interested ? It should be a simple project for him ?


----------



## phooka

I am currently working on a board design that merges this circuit with a transcoder and RGBHV passthrough. when it is debugged I will happily make a board run, and possibly full kits, for the forum.


The transcoder chip is the Nat'l Semiconductor LMN1251. This is a surface mount device. As such I am leaning towards doing the whole board as surface mount, as it makes the layout simpler as the trace length will be shorter.


More to come as I make progress, though I'll start a new thread most likely.


--

Nick


----------



## Steve Smith

Nick that's exactly what I'm looking for. Keep us posted on your progress.


----------



## MarkSel

Hello Nick, put me on the list of interested parties, either for a kit or a ready to go unit.


Thanks


Mark


----------



## picree

Quote:

Originally Posted by *PAW*
picree

How long did it take to build the board and what was the total time to complete the project (stuff it in a box, etc.)? There might be some poor starving EE students near me who would be happy with $25 (tax free) an hour.
Someone here might squak that I'm a slowpoke...so be it...but I'm no EE expert. Sure you could race through the board...but if it don't work then what? I was very careful not to overheat anything...blah, blah.


I built two boards (one w/ BNC and one w/ VGA HD15) and stuffed them in one box. It took about two full days plus a night. But then again, I'm no expert and I had to check EVERYTHING since I would have NO clue how to troubleshoot such a board.


That sounds like a lot but there's:


Research/buying all the parts-4hrs total

Populating the board(s)-~150 pieces/bd-8hrsx2

Building the box-2hrs

Moding the power supplies-0.5hr

Assembly-2hrs

Making the BNC and VGA jumper cables-2hrs

Testing-1hr


So that works out to 14hrs/bd...times $25/hr that's $350 labor plus $150 parts or $500....I don't think its worth it unless someone does an automated run of 25 or so....


...but the picture is soooo cool! In the end darker blacks really make the colors more vibrant...my 2 sense.....


----------



## greekCRTfan

Put me on the laaaaaazy list also!!!!

Realy isnt there anyone to take take care of us?????


He can make same money doing that for 10 pcs or more.


----------



## benny

Quote:

Originally Posted by *greekCRTfan*
Realy isnt there anyone to take take care of us?????
Perhaps it's an appropriate time to refresh members memories of an alternate solution ... http://www.avsforum.com/avs-vb/showthread.php?t=588046 


If you look back through this current thread you will glean the technical nature of my mate's design. Current status of his design is that he has received the PCB back from the fabricator he uses and needs to allocate some of his spare time to populate the board. He has been totally committed to finalising his new cutting edge class A/B amp at the moment and hasn't had any spare time to complete the final step of the gamma circuit. I hope to hear of some progress closer to next weekend though.


Cheers 


Russ


----------



## Boilermaker

First I want to thank tse for his efforts and willingness to share his design with us, and secondly thank picree for helping me obtain the boards!

Now, I seem to have a problem and hopefully it is curable. As soon as I got it assembled, I installed it to check it out but noticed two issues: First, it did not expand the bottom end as it does for others that have had sucess, and secondly it was clipping on whites. To see what was going on, I hooked up my scope to one of the colors and found that while the input was at about .7 volts, the output is running almost twice that (peak to peak). I am using a 1080i signal from a DirecTv receiver as a source as I do not have a signal generator. Also, unfortunately, I am not even aware of what a video signal should look like! The input and output waveforms look virtually identical except for the 2:1 gain. Any ideas on what I screwed up?! The thought of having subtle differences in near black levels with a perfectly black backgound has me peeing my pants!

Thanks,

Bob


----------



## tbrunet

Quote:

Originally Posted by *Boilermaker*
Any ideas on what I screwed up?!

Bob
Did you terminate the input to your scope with (75 ohm) term?


thomas


----------



## tse

Did you have the outputs terminated with 75 ohm loads as will happen when it is connected to a projector? Make sure the pot is turned max clockwise, not like the schematic note says.


----------



## jtnfoley

Quote:

Originally Posted by *greekCRTfan*
Put me on the laaaaaazy list also!!!!

Realy isnt there anyone to take take care of us?????


He can make same money doing that for 10 pcs or more. 
My favorite Starving College Student has stated his willingness to do some board stuffing. This kid is good... good enough that I'm already working to get him hired when he graduates.

He also pointed out that some of the boad fabbers (ExpressPCB? I'm not sure...) do board stuffing for very small quantities.


I have not shown him the design... I just told him ~150 thru-hole parts. If somebody want's to volunteer a board and parts kit he can plow thru the first one and develop a time/cost for the labor.

Alternatively, he's quite capable of sourcing boards and parts. If he sees the design and signs up to do the work, he probably will be willing to take pre-order money to source the parts.


----------



## Boilermaker

tse - Thanks! Yes, with proper loading (75ohms) my gain issue became a non-issue. The clockwise was the problem. All I can say is WOW! The effect is even more dramatic than the change to a high gain torus I did a few month's ago.

I'm using an HDLeeza, so I found I had to change the settings on it and the projector to get the best results. The settings are now actually very close to the factory defaults.

I think I'll go watch "Hunt for Red October" which used to drive me up a wall trying to deal with the darker scenes.

Many Thanks,

Bob


----------



## Briands

Bob,


Noticed you are "in the area"... Do you happen to have an extra board? Where did you get yours?


----------



## buttsplice

Isn't there a way to make a kit at Digikey so that you can just order a certain part # from them and get all the parts for this board at once? That would make things easier until somebody can distribute some of these as kits or fully populated. I'd love to buy the boards/parts for 8-10 of these and resell them but I just don't have the temporary cash sitting around, being the poor starving EE student (who's looking for a job!) that I am  I might be able to swing it after a few paychecks stack up after finals, if nobody else has started making these. Good job tse, you're getting rave reviews!  Now that the pg is back up I'm going to try to replicate your gamma curve in windows, though I first have to figure out why your output has a -100mv offset compared to the input and what this means as far as my software implementation. I'm a video n00b and I think you explained this in the old long thread so hopefully I'll find the answer there.


----------



## Boilermaker

Brian - You have a PM.


----------



## greekCRTfan

Quote:

Originally Posted by *jtnfoley*
My favorite Starving College Student has stated his willingness to do some board stuffing. This kid is good... good enough that I'm already working to get him hired when he graduates.

He also pointed out that some of the boad fabbers (ExpressPCB? I'm not sure...) do board stuffing for very small quantities.


I have not shown him the design... I just told him ~150 thru-hole parts. If somebody want's to volunteer a board and parts kit he can plow thru the first one and develop a time/cost for the labor.

Alternatively, he's quite capable of sourcing boards and parts. If he sees the design and signs up to do the work, he probably will be willing to take pre-order money to source the parts.
So how can we start with it?

Can we feed a little bit your starving college student  ???

PM me the details

thx


----------



## PAW

My checkbook awaits!


----------



## jtnfoley

Is the netlist up to date?

If so, I'lll have make a kit BOM at Allied/Mouser/Digikey (or bits from all three, if there is a compelling cost advantage... say, over ten bucks per board.)


----------



## misohorny

I'm thinking of putting together one of these boards but only populating the video section at first (KISS principle) and trying it out in a Momitsu V880. The only source of HFA1100IP chips I can find is Newark, and their shipping policy is

"We ship to all countries except for Cuba, Iran, Iraq, Libya, North Korea, and Syria. The minimum export order is $250.00."


Can someone direct me to an alternative source with a more reasonable minimum order for a hobbyist in Australia, alternately could someone sell me some HFA1100s?



John


----------



## tse

Any video type current feedback opamp will work. These amps are designed for specific feedback resistor values. If you find a type that you would like to use and it's resistor value is different than the 1100s just post the part number and I'll use my spice program to determine what the other resistors will have to be. No problem.


The circuit will only work if the video at the non inverting input of the video opamp is clamped/dc restored at zero volts.


----------



## misohorny

Quote:

Originally Posted by *tse*
The circuit will only work if the video at the non inverting input of the video opamp is clamped/dc restored at zero volts.
Tse,

I assume, in layman terms, this means that the signal must have zero volts as it's base line. About a year ago I had connected an oscilloscope (via a T connector on the red BNC) between the Momitsu and my projector, and I seem to remember that was the case. Playing with the brightness and contrast of the Momitsu shifted the signal in relation to the base line which itself didn't move. Anyway, if the stripped video circuit doesn't work, I'll populate the rest of the circuit board. If it does I'll cut down the board and tuck it inside the Momitsu.
Quote:

Originally Posted by *tse*
Any video type current feedback opamp will work.
That's easy for you to say  . Thanks for the offer to work out the resistors, but I'll try to get some 1100s. You've done more than enough.


John


----------



## dokworm

If anyone in Oz can source all the bits, I'm happy to play solder monkey and assemble them for the Aussies.


----------



## dokworm

Any more movement on this?

I think this could be a huge deal if it works...


----------



## jtnfoley

Workload is settling, so I can re-invest in this project. I'll speak to my uber-student probably tomorrow, but I still don't have an answer regarding the netlist.

Does the published netlist reflect the absolute latest design?


----------



## dokworm

Perhaps a new thread is in order explaining exactly what this does, and asking if people are interested in a 'bulk buy'.


This is potentially one of the biggest boosts for CRT projectors I've seen in a long long time, I just think a lot of people on the board don't quite understand what a big difference this would make to their setup. A new thread with a bit of a description (perhaps quoting some specific movies that give headaches on CRTs - Master and Commander is one for me...) and there should be a lot of people interested.


We could then get a raft of boards made. I'd be happy to assemble and test them for free for the Southern hemisphere and send them onwards.

For that matter I'd be happy to send them anywhere if people would pay postage etc. as long as it wasn't hundreds.


----------



## jtnfoley

Hikes! Careful, Dok... there's something like 150 discreets on this, and they are all thru-hole!


----------



## dokworm

Yeah, but I solder for relaxation... the lead calms me 


Seriously though, obviuosly it wouldn't be possible for me to make hundreds of them, but I think it would be worthwhile getting as many people as possible to participate in a buy and either assemble them themselves or get someone esle to put it together for them in their area.


If not many people south of the equator were interested and people in the North couldn't find a local assembler I'd be happy to help out.


----------



## tse

Quote:

Originally Posted by *jtnfoley*
Hikes! Careful, Dok... there's something like 150 discreets on this, and they are all thru-hole!


Don't be afraid of the thru-hole. ;-)


Prop the board up on the edges with a couple of books, stuff the parts, and solder from the top side. Makes quick work of it!


When you ask about the net-list do you mean the gerbers or are talking about the parts list/


----------



## Chris Bigos

Quote:

Originally Posted by *jtnfoley*
they are all thru-hole!
As opposed to - - - what? A "non-thru-hole"? Is a non-thru-hole a hole?


----------



## jtnfoley

Quote:

Originally Posted by *tse*
Don't be afraid of the thru-hole. ;-)


Prop the board up on the edges with a couple of books, stuff the parts, and solder from the top side. Makes quick work of it!


When you ask about the net-list do you mean the gerbers or are talking about the parts list/
Parts list.


First step in building a quote is to build a parts package. (Referring to my uber-student who is willing to stuff boards for this effort.)

I can build a parts list and save a BOM at one or more of the major suppliers, uber-student can evaluate how much time he'll require to stuff and test.


And, if I ever get off my arse and finish the combined transcoder/tse gamma circuit, he may be able to stuff a quantity of these. Absolutely no idea for an ETA on these.


----------



## tse

The parts list is correct. The only change should be the LT1213 op-amps. To save some bucks use MC33077.


----------



## Laser117

Less than $200, count me in. I wouldn't mind a kit form either, but I'd rather have a turnkey solution. External. For my Ampro 2k.


----------



## WTS

Hi tse,


Actually I think there is a mistake on your parts list. The BNC's you have listed are 50ohm bnc's not 75ohm, I have the 75ohm part #s at home that I'll post later.


----------



## tse

WTS, I think you are right. Those are 50 ohm jobs but they work ok. The right part number will be appreciated. Thanks.


----------



## misohorny

Quote:

Originally Posted by *misohorny*
Thanks for the offer to work out the resistors, but I'll try to get some 1100s. You've done more than enough.


John
Tse,


actually can I take you up on that offer? I've bought some CLC446AJEs, not PDIP, but I'll be etching my own version of your board and hand drilling 24 less holes is no loss. So the $64k question, is the CLC446 good enough, and what would the revised component values be?

Datasheet (445KB pdf)


Cheers,


John


----------



## dokworm

Hey Miso, if you create a board mask, would you mind posting it? I have a pair of momitsus that would like an internal solution...


----------



## moome

guys, why not try my transcoder?


----------



## PAW

Quote:

Originally Posted by *moome*
guys, why not try my transcoder?
Moome. Are you saying that your DVI/Component to VGA transcoder increases the gamma curve at low IRE levels?


----------



## Person99

Quote:

Originally Posted by *moome*
guys, why not try my transcoder?
Moome, I actually emailed you a month or so ago and pointed you at this thread. I asked the viability of including this circuit in your transcoder. I did not hear back from that email, but assume that it was not included in the transcoder as I have your transcoder and it does not seems to modify the gamma curve like this.


Dave


----------



## WTS

Hi Dave,


No problem I already included it into his design, but only as part of the tcoder circuit. I suppose that could be changed to include the HDMI circuit as well.


----------



## Ericglo

So moome's transcoder has tse's gamma circuit. That is good to know.


Ericglo


----------



## WTS

Yes I asked tse if it would be okay and he said no problem as long as I gave the credit to him for the circuit, not sure who else I would give it to as everyone knows who did the circuit. So heres to tse.


----------



## WTS

Hi tse,


Heres a couple of part #s for the 75ohm bnc pcb mount type, Digikey # A32405-ND or A30569-ND.


----------



## Laser117

TSE's gamma circuit is in moome's transcoder? The transcoder that takes HDMI input and sents out RGB? Can it strip HDCP? Does anyone have this to offer up any experiences with a final product?


Anyone want to buy a VDigi transcoder?


----------



## tse

Quote:

Originally Posted by *WTS*
Hi tse,


Heres a couple of part #s for the 75ohm bnc pcb mount type, Digikey # A32405-ND or A30569-ND.
Now I remember why I used the 50 ohm part.


The above Digi-Key parts are $5.08.


Digi-Key is out of the part in the parts list but Mouser has them for $1.70.


The Amp part number is 227161-9


The 50 ohm parts work just fine.


----------



## VideoGrabber

> _I already included it into his design, but only as part of the tcoder circuit._ 
_So moome's transcoder has tse's gamma circuit. That is good to know._


----------



## dokworm

Quote:

Originally Posted by *misohorny*
Tse,


actually can I take you up on that offer? I've bought some CLC446AJEs, not PDIP, but I'll be etching my own version of your board and hand drilling 24 less holes is no loss. So the $64k question, is the CLC446 good enough, and what would the revised component values be?

Datasheet (445KB pdf)


Cheers,


John
tse, do you reckon these will work?


----------



## Person99

Quote:

Originally Posted by *WTS*
Hi Dave,


No problem I already included it into his design, but only as part of the tcoder circuit. I suppose that could be changed to include the HDMI circuit as well.
I've mostly been playing with the DVI side so that explains why I've not seen it. Thanks for the clarification.


Dave


----------



## Person99

Quote:

Originally Posted by *Laser117*
TSE's gamma circuit is in moome's transcoder? The transcoder that takes HDMI input and sents out RGB? Can it strip HDCP? Does anyone have this to offer up any experiences with a final product?


Anyone want to buy a VDigi transcoder? 
Read Walter's post a couple above this. tse's circuit is only on the component side, not the DVI side.

Quote:

Originally Posted by *VideoGrabber*
I'm not sure I understand. Is it in the design (for future implementation), or the currently shipping build versions?
The component side of the currently shipping device has this (see Walter's posts above)


I'm the one that said I did not see it. I did not see it because I have been mostly playing with the DVI side and it is not included there.


Dave


----------



## WTS

Hi,


No, the currently shipping Moome card does not have the tse circuit included and I had nothing to do with his current run of cards. The tse circuit will be included on the new HDMI/HD component card, but when it will be available I don't know yet as Moome is fairly busy these days so it may take some time yet.


----------



## Person99

Quote:

Originally Posted by *WTS*
Hi,


No, the currently shipping Moome card does not have the tse circuit included and I had nothing to do with his current run of cards. The tse circuit will be included on the new HDMI/HD component card, but when it will be available I don't know yet as Moome is fairly busy these days so it may take some time yet.
Sorry, I misunderstood you Walter. I don't believe tse has announced this product yet. But, you've saved me the time of testing the component side of the current one!


Dave


----------



## tse

Quote:

Originally Posted by *misohorny*
Tse,


actually can I take you up on that offer? I've bought some CLC446AJEs, not PDIP, but I'll be etching my own version of your board and hand drilling 24 less holes is no loss. So the $64k question, is the CLC446 good enough, and what would the revised component values be?

Datasheet (445KB pdf)


Cheers,


John
I believe those parts will work fine. Read the part of the spec sheet concerning pcb layout carefully.


Resistor values as soon as I can transfer some files from my old pc to the new one.


----------



## Semisentient

Quote:

Originally Posted by *WTS*
Hi,


No, the currently shipping Moome card does not have the tse circuit included and I had nothing to do with his current run of cards. The tse circuit will be included on the new HDMI/HD component card, but when it will be available I don't know yet as Moome is fairly busy these days so it may take some time yet.


That's great news. I was going to buy the external box so I could still use my tse circuit, but if the new cards will have it internaly, that's worth waiting for!


James


----------



## Laser117

I want one...LOL...


On one hand, I'm thinking, hurry up...and on the other, I have to find nearly $300.......


Has anyone besides TSE gotten the circuit to work and played with it? Is it that amazing? I'm hoping this will make my Ampro finally sing...I have such issues with shadow detail.


I assume Moome's decoder does not crush blacks either....


Anyone got any info on Moome's Ampro implementation? I'm thinking I'd rather go external, and obviously, I want TSE's circuit in there if I'm going to do it.


But I'm curious about the Ampro card...


----------



## WTS

The ampro card will only be for the x300 and x600 series pjs.


----------



## Semisentient

Quote:

Originally Posted by *Laser117*
I want one...LOL...


On one hand, I'm thinking, hurry up...and on the other, I have to find nearly $300.......


Has anyone besides TSE gotten the circuit to work and played with it? Is it that amazing? I'm hoping this will make my Ampro finally sing...I have such issues with shadow detail.


I assume Moome's decoder does not crush blacks either....


Anyone got any info on Moome's Ampro implementation? I'm thinking I'd rather go external, and obviously, I want TSE's circuit in there if I'm going to do it.


But I'm curious about the Ampro card...
I use the circuit (traded tse for it...) and it makes a marked improvement.


Moome's prices are very good.



James


----------



## Ericglo

James,

I thought you made it. What was the price? Your immortal soul.


Besides JT, there is also Buttsplice who is willing to make the board.



Ericglo


----------



## WTS

Hi James,


What pj are you running.


----------



## Tom.W

I will let Moome comment on this but Moome's card does not have tse's circuit in his latest converter as far as I know but a sort of gamma correction circuit for his converter.I received a response to a PM I sent to Moome on the Evil Twin today . He would like to produce a run of tse's boards but needs the latest circuit board and any changes those of us here would like to see before he goes into production.


----------



## tse

Schematic for the CLC446 opamp. These resistor values are calculated and I have not tested them as I don't have a CLC446 part to try. But, I think that this will work as intended. If you have access to a pulse generator check the response. R3 has a big influence on the rise and fall time as well as the overshoot. Too much overshoot and R3 needs to be a larger value, low bandwidth and R3 should be a lower value. R1, R2, and R101 are tied to R3's value.


----------



## Semisentient

Quote:

Originally Posted by *Ericglo*
James,

I thought you made it. What was the price? Your immortal soul.


Besides JT, there is also Buttsplice who is willing to make the board.



Ericglo
I traded him a Samsung TS-360. He had an extra board since he had to order two when he had it made. I don't think he is interested in making more himself.


----------



## Semisentient

Quote:

Originally Posted by *WTS*
Hi James,


What pj are you running.


Sony 1292Q, Momitsu 880DX and tse's Gammafixerator!


----------



## dokworm

Quote:

Originally Posted by *tse*
Schematic for the CLC446 opamp. These resistor values are calculated and I have not tested them as I don't have a CLC446 part to try. But, I think that this will work as intended. If you have access to a pulse generator check the response. R3 has a big influence on the rise and fall time as well as the overshoot. Too much overshoot and R3 needs to be a larger value, low bandwidth and R3 should be a lower value. R1, R2, and R101 are tied to R3's value.
Thanks tse, we owe you some Aussie beer.


Miso and I will probably make one each and let you know how it goes.


You're not interested in doing some laserdisc modding now are you


----------



## Tom.W

I want one of tse's cards for my Momitsu DX and to use with the MP-5 . The Gamma is pretty good on the MP-5 but the DX needs a bit of help


----------



## Laser117

Quote:

Originally Posted by *WTS*
The ampro card will only be for the x300 and x600 series pjs.
Thanks for the info. I guess that just makes it a tad bit easier to go with external, eh?


----------



## Ericglo

How much more for moome's card with the gamma circuit installed?


Ericglo


----------



## Tom.W

Moome's card is smaller than tse's card so I assume he will try a simple outboard unit with component in and component out . Now if he could incorporate the circuit into his external component/ DVI/HDMI converter and could get it to work via HDMI also that would be special !


----------



## WTS

Hi,


As far as Moome's next card goes, yes it will have tse's circuit on it and no it is not as big a board as tse's as I'm not using all of tse's circuit only whats needed for my design. His circuit was designed as a stand alone circuit when then required alot more circuitry to make it compatable with the outside world so to speak.

Will the HDMI go through the tse circuit, yes more than likely I will change it so that it will, but Moome hasn't given me the go ahead if he wants it that way and the HDMI part of the board is his design not mine. But I'm sure that he will want to do what the masses want.


The function of the board will be basically the same whether its an internal or external unit.


I really hope that this ends all the speculation that seems to be circulating around about this new board.


As far as know Moome hasn't set a price for the new board yet because the design isn't complete yet.


----------



## PAW

HMM!!! Think Moome would be willing to add RGB passthrough? Going through the gamma circuit of course. Could kill 3 or 4 birds at once.


----------



## moome

i have put this gamma circuit on ampro card, but need time to make it . i am busy for my new job and make sony and marquee card


----------



## WTS

Hi,


Well I suppose most anything could be done thats not the problem. The problem is to make it affordable, as you've probably noticed Moome's cards are very well priced(low) and I'm sure he'd like to keep it that way. Now you keep adding things and pretty soon it won't be priced affordable anymore and then he won't sell as many etc etc.

Maybe someone could start a poll as to what everyone would like to see and how much they would be willing to pay for. Then Moome could make a decission from that, maybe.


----------



## Person99

Quote:

Originally Posted by *PAW*
HMM!!! Think Moome would be willing to add RGB passthrough? Going through the gamma circuit of course. Could kill 3 or 4 birds at once. 
Excellent idea!!! Let me add one other.


OK, here is the feature list for the killer box:

Inputs:

1 x HDMI

1 x Component

1 x RGBHV (passthrough)


Outputs:

1 x RGBHV


Configurable options:

- Input priority (prioritization order if signal on two or more inputs)

- Use altered gamma or not (on/off - applies to all inputs)


Opinions?


Walter, Moome...thoughts?


Another perk might be to add a component output so that the box has even broader appeal since there are an estimated 6.6 million HD displays owned in the U.S. alone that only have component input and even more that are not HDCP.


You could also offer a higher end model that takes away input prioritization and offers more inputs and functions as your switcher. Maybe something like 3 HDMI and 2 Component, but then you have to get into IR control and shipping a remote, etc.


Dave


----------



## Tom.W

Quote:

Originally Posted by *Person99*
Excellent idea!!! Let me add one other.


OK, here is the feature list for the killer box:

Inputs:

1 x HDMI

1 x Component

1 x RGBHV (passthrough)


Outputs:

1 x RGBHV


Configurable options:

- Input priority (prioritization order if signal on two or more inputs)

- Use altered gamma or not (on/off - applies to all inputs)


Opinions?


Walter, Moome...thoughts?


Another perk might be to add a component output so that the box has even broader appeal since there are an estimated 6.6 million HD displays owned in the U.S. alone that only have component input and even more that are not HDCP.


You could also offer a higher end model that takes away input prioritization and offers more inputs and functions as your switcher. Maybe something like 3 HDMI and 2 Component, but then you have to get into IR control and shipping a remote, etc.


Dave
Hi Dave,

This sounds really great but for now I just need someone to build one of tse's boards using tse's design for use with my Momitsu and the MP-5 . So many here have asked for a pre built unit but none that are willing to do so have announced a price.

I just thought Moome could come up with a good price on these if there was enough interest.I could be wrong about the interest part...


----------



## Belcherwm

I'm still very interested.


----------



## buttsplice

Ok, finals are done Monday so I'm ready to build some of these. Who is still interested? My initial cost analysis shows the price to be less than $200 but probably not by much, which includes a wall adapter wired with a connector to hook into the board's dual-supply header. Who would be offended by having two wall adapters on their power strip for this board? Having two adapters (or a dual output DC adapter if somebody knows of one) is the best way to power the board since it allows a small input capacitor size and causes less dissipation in the regulators due to lower voltage, but is obviously a little more obtrusive than having a single AC adapter feeding both inputs. The heat from the regulators might be a significant worry for folks putting these in closed cases so I'd prefer the dual-adapter option.


Let me know if you're seriously interested in a board at this price range and if you have objections about the dual adapters, let them be known.  This arrangement seemed well accepted at the evil twin forum so if there's also still interest here then I'll order the parts this week and aim to ship the first ones by late next week, assuming the board house gets boards to me swiftly.


----------



## PAW

Hi Eric


I'm still interested but have a few questions


1 - So the purpose of 2 power supplies it to supply 2 different voltages? I would PREFER one adapter.

2 - What is NOT included in the price? I'm assuming no case or BNC cables. What about the power adapters, BNC connectors, etc.

3 - If you settle on 2 adapters, please keep them as small as possible. I've seen adapters with short AC cords, so the adapter sits on the floor. Though they tend to be must LARGER adapters. I've also seen short AC extension cords. So, your adapters don't cover up other outlet on your power strip.

4 - What steps will be left to stuff these in a case and make them fully usable. I've never built anything electronic.

5 - Would a vented case help with the heat?

6 - What type of testing on each board would you do and what type of warranty? For a warranty I was thinking of no DOA not a lifetime warranty. Not that I'd trust you but I don't have the capability to R&R this stuff.


Thanks for looking into doing this. Be sure you at least get beer money out of it.


----------



## buttsplice

I should note that the AC adapter by design doesn't imply higher dissipation, only that the particular one I found cheaply would yield a fairly high input voltage. The selection of cheap DC adapters is much better than the AC variety but I'll keep looking for a better one.


No case or BNC cables are included, but electrically this will be useable as it ships. I'll burn each unit in on my projector and make sure everything looks right with some test patterns. No DOA for sure. I'm reasonable so we can work something out if issues arrise.


----------



## Tinman

Seriously interested!! 


Marc


----------



## buttsplice

OK, thanks to our good friends at Google, I have found an AC adapter that will do the trick, so no dual adapters!


I recalculated with price breaks and here's my official pricing:


$192 with AC adapter (120V only) wired with push-on connector

$186 without AC adapter (power connector and pins included)


I will include the 156mil 4-pin connector housing and crimp pins with the latter package since you'd probably have trouble finding that locally. There is a high dollar tool that's used to crimp them but you can do it with needle nose pliers if you're careful. I will include extra pins for the inevitable 


PM me with serious intentions to buy and indicate if you need the adapter or not. This is not an official purchase but I'm buying parts this week so I need the count to be as accurate as possible.


Shipping is additional and will be USPS actual cost with insurance.


----------



## tse

One of our friends on the forum asked for gerber files of two boards, so here they are. I added the 220K resistors and disconnected pin one of the blue HFA1100 from the ground plane. Let me know if I've missed anything.


The two boards don't exactly line up, check and make sure that that is ok.


The *.pcb file is included as well as the ascii netlist.

 

AVS_Gamma_Rev01.zip 421.650390625k . file


----------



## jamieh

Maybe i missed something here or i didn't catch it in the previous posts but i have a couple of assumptions/questions.

I,m assuming 5 bnc in/out,s and is there some kind of user adjustment for the amount of gamma correction?

I,m also wondering if if person was so inclined if the physical dimensions of this unit would allow it to be placed near the VIM board of a Marquee as an internal add on and bypass the need for another set of bnc cables?

Jamie


----------



## tse

Quote:

Originally Posted by *jamieh*
Maybe i missed something here or i didn't catch it in the previous posts but i have a couple of assumptions/questions.

I,m assuming 5 bnc in/out,s and is there some kind of user adjustment for the amount of gamma correction?

I,m also wondering if if person was so inclined if the physical dimensions of this unit would allow it to be placed near the VIM board of a Marquee as an internal add on and bypass the need for another set of bnc cables?

Jamie
There is RGB in and RGB out as well as h sync in and h sync out. This circuit doesn't need v sync.


The gamma can be adjusted but only by changing component values. The intent of this board is to boost the darker portion of the video allowing the projector brightness control to be turned down to the point that black is black without loosing shadow detail.


You could probably make a plug in card for the Marquee using this circuit if you used surface mount parts.


----------



## Budget Pete

I think I want one of these, but I'm not sure.


This will help me see detail in movies like Million Dollar Baby, Master and Commander and other dark movies where currently I just see a lot of darkness and not much detail yes?


I just plug it in between my PC or momitsu and the projector and it works it magic automatically?


I am also looking for a good transcoder, should I just buy one and use it with this, or is there a standalone transcoder with this type of circuit in it already?


----------



## ChrisWiggles

Quote:

I just plug it in between my PC
If your PC is your source, you already have gamma control options with most any new video card/drivers. This is not designed as a "new" thing, this circuit is simply for sources that don't have gamma adjustments or situations where you can't adjust gamma and want a way to do it. If you're using a PC or processor or other device that allows you to adjust gamma, then you don't need this circuit.


A lot of people seem to be missing that point. this isn't a "magic" device that will overcome ANSI limitations of a display, it's just a gamma adjustment, and if you can already adjust gamma (as anyone with a PC source or processor usually can) then it's not anything new, because likely you've already adjusted gamma a long time ago if you desired to, or at the very least now you are aware that this adjustment exists in your system, so you can adjust it if you wish.


I really don't want to discourage anyone from using gamma adjustments, or TSE's circuit, I think it's a great thing for the times you need/want to adjust gamma but currently can't. But at the same time, I think a lot of people are misunderstanding this, and thinking that this is a "new" thing that didn't exist before. All it is, is a solution for the sources that DON'T already have gamma adjustments but you want to adjust the gamma. If you already have sources with gamma adjustments, or you don't want to adjust the gamma, then you don't need this.


-Chris


----------



## jtnfoley

Quote:

Originally Posted by *Budget Pete*
I think I want one of these, but I'm not sure.


This will help me see detail in movies like Million Dollar Baby, Master and Commander and other dark movies where currently I just see a lot of darkness and not much detail yes?


I just plug it in between my PC or momitsu and the projector and it works it magic automatically?


I am also looking for a good transcoder, should I just buy one and use it with this, or is there a standalone transcoder with this type of circuit in it already?
There are a few of us flirting with the idea of combining a gamma-correct-o-matic circuit with a transcoder, search this thread.

If I survive the next few weeks I may return to working on mine.


There's also another gamma correction circuit mentioned in this thread (which also lacks a transcoder) that may be produced in small commercial quantaties somewhere in Australia.

Perhaps you could drive on over and demo one of those... Australia's an island, right? How big could it be?    (Probably be cheaper and faster to overnight something from the states than to ship cross-corners across that island continent.)


----------



## YONEXSP

I don't think my PowerDVD6 has gamma adjustment lol!!!


----------



## jtnfoley

Quote:

Originally Posted by *YONEXSP*
I don't think my PowerDVD6 has gamma adjustment lol!!!
Does your graphics driver?


----------



## PAW

Quote:

Originally Posted by *Budget Pete*
I think I want one of these, but I'm not sure.


This will help me see detail in movies like Million Dollar Baby, Master and Commander and other dark movies where currently I just see a lot of darkness and not much detail yes?


I just plug it in between my PC or momitsu and the projector and it works it magic automatically?


I am also looking for a good transcoder, should I just buy one and use it with this, or is there a standalone transcoder with this type of circuit in it already?
Budget Pete


I don't have one of these, yet. However, the answers are


Yes


Yes


No. There's talk of Moome adding it to his but nothing definiate.


----------



## picree

tse-my friend may have pm'd you. He swears he was getting a red-shift on very high gamma scenes (snow, beaches, sand). Bad component? I haven't seen it yet myself but it got me wondering. Have you given any thought to changing the variable 50k resistor to some other value or a fixed resistor? For his setup and mine the best results were with the resistor maxed out in one direction (cw I think). Anything else seemed less than ideal. I would have felt better if best results were in the middle somewhere.


You explained it's purpose once (back porch, zero volts...) but I forget exactly.


picree


PS-the card has enabled me to finally see Macroblocking  (a bad thing I suppose). I actually have to turn DOWN the brightness on some HD shows!


----------



## Budget Pete

So for my PC source I can just adjust gamma somehow?


----------



## ChrisWiggles

Yes, there's usually a fairly advanced complement of gamma adjustment options in your video card settings. This of course varies depending on video card, drivers, etc. A lot of drivers allow you to make spaghetti out of your gamma if you so desire, so the adjustments can be as complex as you want to make them. Obviously I suggest standard curve adjustment, and conservative at that or you begin to crush depth in bright scenes by reducing contrast at the upper portion of the curve.


----------



## dokworm

Sounds like a new thread is in order with a 'how to' for some common video cards...


----------



## 1031

Hey TSE.. Is that possible to replace those 10micros bipolars whit sanyos OS-cons. I have modded my sony 1272 rgb-signalroutes whit those OS-cons and they make "huge" improvement to details..


----------



## tse

I used bi-polar caps because I don't know what DC bias the input video will be riding on. The side of the cap that connects to the circuit will be at zero volts. If the input video is riding a positive DC level then place the + side of the cap toward the video input.


----------



## tbrunet

A bi-polar cap has no marked polarity..it can be made by connecting two polarized caps in series, and the two negative negative should be leads conected together.


thomas


----------



## tbrunet

A no-polar cap has no marked polarity, on can be made with two polarized caps in series with the negative leads being common..sorry if this obvious and un necessary.


thomas


----------



## GEBrown

Quote:

Originally Posted by *1031*
Hey TSE.. Is that possible to replace those 10micros bipolars whit sanyos OS-cons. I have modded my sony 1272 rgb-signalroutes whit those OS-cons and they make "huge" improvement to details..
1031


Would you mind starting a new thread describing what you did to your 1272? I don't remember ever reading about such a mod here in the forum.


With pictures?


Thanks


----------



## tse

There have been some questions about where to set R21. For most, if not all, applications set it max CW. If turned CCW far enough the sample gate will move out of the horizontal blanking interval and into the video. You don't want the gate to be in the video.


When I first started with this project I was anticipating tri-level sync on the green video and wanted a way to place the gate at the back porch. Since then I found that RGBHV signals are common and tri-level sync is not too common with the sources that I'm interested in.


The attachment shows a little more detail about this.


Ok, you guys that don't have some means of adjusting the shadow detail of your video source are missing out if you don't have this or something similar. Your heart almost stops when a scene ends and the screen goes completely black. Especially if you are in a totally dark room. The thought "what happened?" flashes through your mind. Until the next scene starts. This is with the brightness set for good shadow detail. No gray raster up on the screen between scenes.


----------



## picree

He's right you guyssss! Why all the hemming and hawing? Get off your butts. It's a FUN project...you're off for the Christmas Holiday right? Order your parts tonight! It's the best $160 stinkin' bucks you'll spend on your whizz bang projector, I can tell you that.


I suppose a hushbox would be nice but if you really want a better picture......


This is a significant upgrade for a non-HTPC CRT setup. It ranks right up there with getting the color corrected/filtered lenses/glycol and a good gray-scale.


Black is BLACK!  It IS heart stopping. My family is truly sick of hearing me say, "Is that black or what?!" And guess what? Blacker black improves the intensity of all the colors! The picture just looks darn good 



I've built two of these boards, one for the DVD input (5) and one for the HDTV OTA input (3). Once you've seen black, you'll never go back!


picree


----------



## Chris Bigos

Quote:

Originally Posted by *tse*
When I first started with this project I was anticipating tri-level sync on the green video and wanted a way to place the gate at the back porch. Since then I found that RGBHV signals are common and tri-level sync is not too common with the sources that I'm interested in.
So if I know I'm only going to be using it with RGBHV (which I do) then I can replace VR21 with a link? The 2.2K R14 will still provide the time constant to put the sample in the "safe zone"?


Still getting my act together to actually stuff the board.


----------



## tse

Yep, replace R21 with a link if you will be using RGBHV.


----------



## Chris Bigos

OK - thanks TSE.


I have an 18V PSU (many old HP printers use them so loads kicking around). Couldn't I just connect the +ve to F1 and the -ve to F2 and let them float w.r.t. ground?


----------



## 1031

Quote:

Originally Posted by *GEBrown*
1031


Would you mind starting a new thread describing what you did to your 1272? I don't remember ever reading about such a mod here in the forum.


With pictures?


Thanks
Maybe later.. im so busy at now..


Hey TSE. Have you tried to make voltage divider network whit resistors for that at peoples can use singlevoltage powersuppy. i havent tried that at this project, but i think that powerconsuption at those +-5 volt lines is not so big.


----------



## tse

Hmmm, I can't think of a reason why you can't connect one supply. Let me think on that one. The current draw is slightly less than 0.1A on each rail.


----------



## Chris Bigos

Yeah - I figure it will find a ground reference through C5 and C22. It would only work if the 18V supply I'm suggesting is fully isolated. I'm assuming that's the case, but will need to check.


----------



## 1031

(47-100 ohm/2-5w could work)

_______________________Resistor______________ To positive regulator

+ /

/ /

/

/

/

}__________________ "Ground"

Input 15-18vdc \\

\\

\\

\\

_- _____________________Resistor___\\___________ To negative regulator


Here is that "simple powersupply". i havent testet that for this project but for another project what used +- voltages this worked ok. I did regulation using 1.3w 5.1 volt zeners. And of course there must bee caps.. for input 470u 25v is ok and between that "ground" and those +/- lines 100u 25v is ok.. This is just idea.. and it works when powerconsuption is little and powersupply for input is isolated.


----------



## 1031

Quote:

Originally Posted by *Chris Bigos*
Yeah - I figure it will find a ground reference through C5 and C22. It would only work if the 18V supply I'm suggesting is fully isolated. I'm assuming that's the case, but will need to check.
you need to create ground for that.. just tested supplying 17 volt dc to two 100ohm/2w resistor, resistors are between + and - poles of that 17volts so ground is taken from midpoint of that serialconnected resistors and then connect that ground to "raw" connectors ground and + is taken from positive side of those resistors and - is taken from negative side....Sorry for my english skils 


That should work ok if input voltage is near 15-18volt. And check that after regulators there is + and - 5 volts..


----------



## jtnfoley

Why not find an appropriate dual-output regulator and just feed +18 and ground off of acheap brick du jour?


----------



## tbrunet

Quote:

Originally Posted by *1031*
ground is taken from midpoint of that serial connected resistors and then connect that ground
A split supply cannot be produced from a simple resistor network..


thomas


edit: http://tangentsoft.net/elec/vgrounds.html


----------



## tbrunet

Quote:

Originally Posted by *tse*
I used bi-polar caps because I don't know what DC bias the input video will be riding on. The side of the cap that connects to the circuit will be at zero volts. If the input video is riding a positive DC level then place the + side of the cap toward the video input.
I maybe mis-understanding your post (sorry in advance) if my response is un necessary  a bi-polarized cap has no marked polarity, also a bi-polar cap can be made by using two polarized caps in series, the two negative leads should be common.


thomas


----------



## 1031




tbrunet said:


> A split supply cannot be produced from a simple resistor network..
> 
> 
> thomas
> 
> 
> 
> 
> I disagree.. because i tried that and it worked.. similar circuit like on that link.. "resistor divider network" just change those resistors to 100ohm/2 watt and use normal singlevoltage supply instead of that battery. That "virtual ground" works bacause powersupply is isolated, and powerconsuption on those + and - rails is low.


----------



## tbrunet

I agree your circuit will power up and function, and if something works great, but there are considerations i.e.


This virtual ground often crucially determines overall circuit performance. A crude way to generate a midrail reference uses two resistors as a divider, with a capacitor to ground to help attenuate power-supply noise. And therein lies the first problem: Any remaining power-supply noise feeds directly into the reference input and adds to input-signal noise. In dc terms, the circuit's output impedance equals the resistor values in parallel, and ac response is poor, introducing frequency-dependent distortion.


----------



## jtnfoley

The circuit needs +5, gnd, and -5, right?


How about a 6V wall transformer and this (for a buck
http://www.mpja.com/productview.asp?product=2308+PS 


(Is 70mA going to be enough on the -5V rail?)


----------



## 1031

Quote:

Originally Posted by *tbrunet*
I agree your circuit will power up and function, and if something works great, but there are considerations i.e.


This virtual ground often crucially determines overall circuit performance. A crude way to generate a midrail reference uses two resistors as a divider, with a capacitor to ground to help attenuate power-supply noise. And therein lies the first problem: Any remaining power-supply noise feeds directly into the reference input and adds to input-signal noise. In dc terms, the circuit's output impedance equals the resistor values in parallel, and ac response is poor, introducing frequency-dependent distortion.
Ok. If the supply isnt regulated there can be problems like you sayd. Then add smoothingcapasitor at inputside maybe 1000u 25v or bigger, and there is regulators for those +-5 volts and after regÂ´s there are many capasitors to make voltages stable..Of course its better if you use double sided supply, but iÂ´m just saying this because this makes powersupply easier for this project..

Maybe TSE you can trye this and tell your opinion.


----------



## 1031

Quote:

Originally Posted by *jtnfoley*
The circuit needs +5, gnd, and -5, right?


How about a 6V wall transformer and this (for a buck
http://www.mpja.com/productview.asp?product=2308+PS 


(Is 70mA going to be enough on the -5V rail?)
I think that 70mA is little too low..

Because i tested similar product
http://www.tracopower.com/products/index.htm 

It was tma... something +-5volts 100mA out. and That was near ok but regulation was not perfect. Maybe if you found somethin like +-8-10 volts and 200Ma or more and let the regulators do that + - 5 volt.


----------



## picree

You need a minimum of 100 mA for each leg, plus/minus........150-200 ea. is better


----------



## tse

Yep, I'll agree with that. I monitored the current with a nice clamp-on type current meter and it was reading 90-95mA on the positive side and 85-90mA on the negative side. The scene brightness had an effect on the current with the brighter scenes drawing more current.


----------



## 1031

Ok I tested little more that voltagedivider supply and tbrunet was right ,there was some problems... At my workplace it worked ok but when i connected it in my system at home there was little proplems  so i decidet to use doublesided supply.


----------



## GScott

So what's the latest on this circuit being included in Moome's DVI card? I was going to order one of his cards for my G70 after the 1st of the year but would like the gamma circuit as well.


----------



## picree

tse and others-


I have been following another thread discussing the merits of replacing the standard Mercon (sp?) caps that are in the video chain with higher quality caps like Black Gates or Os-cons.


The thought occured to me that the tse board might benefit. It may only be a matter of opinion but I was wondering what you and others in this thread think.


Specifically, I was looking at C8 (maybe replace with a Black Gate) and C7 (an Os-con) on the video circuit. They seem to be the only two that are directly in the video chain. What do you think? Any others that might effect the video quality?


Picree


----------



## picree

OOppss....double-post.


----------



## RGBHV

Did anyone come up with a working kit or Preassembled unit yet ?


Do we know what the price(s) are yet?


Thanks!


Brian


----------



## Ericglo

Brian,

Buttsplice is supposed to be working on it. I am going to call him tonight and see what his time frame is. Even if he doesn't do it, there is still Moome's upcoming card.


Ericglo


----------



## Tom.W

Buttsplice just posted an update on the twin but...


----------



## RGBHV

Eric,


Do you know Moome has it included in the external box, that I think is still in pre-order?


Thanks!


----------



## 1031

Quote:

Originally Posted by *picree*
tse and others-


I have been following another thread discussing the merits of replacing the standard Mercon (sp?) caps that are in the video chain with higher quality caps like Black Gates or Os-cons.


The thought occured to me that the tse board might benefit. It may only be a matter of opinion but I was wondering what you and others in this thread think.


Specifically, I was looking at C8 (maybe replace with a Black Gate) and C7 (an Os-con) on the video circuit. They seem to be the only two that are directly in the video chain. What do you think? Any others that might effect the video quality?


Picree
I used os-cons instead of bipolars... +side towards input side and it works ok. I think that there was only those 3 bipolars in signalchain.


----------



## Tom.W

Quote:

Originally Posted by *RGBHV*
Eric,


Do you know Moome has it included in the external box, that I think is still in pre-order?


Thanks!
I recieved an e mail from Moome this morning and no the gamma circuit is not yet available on Moome DVI cards but he is considering it but has been very busy with work. If he includes tse's design intact it would also require a larger case and different power supply I would suspect.


----------



## RGBHV

Thanks for the update, Tom.


----------



## picree

I'm being lazy today...with respect to capacitors shown on Barco schematics, does anyone know what "K" mean?...as in "300K". I know 100M is 100 microfarads. P is picofarads but what is K?


----------



## buttsplice

Capacitor coding is somewhat hit or miss but many of them follow this format, where K would be a +/- 10% tolerance and 300 would be 30 pF:

http://xtronics.com/kits/ccode.htm


----------



## picree

Thanks for the reference...good info for us hacks.....


----------



## buttsplice

For those still wanting tse's standalone board, please see the poll at the Evil Twin forum. We can finally move ahead with building these if you still want them.
INTEREST POLL


----------



## dustobub

Link doesn't work. I'm down with actually getting these things made. Been waiting for a while.


Dustin


----------



## RGBHV

I am interested in this as well. Is there an idea on what current production run costs would be?


----------



## PAW

Dustin

That website has been hacked. See the Evil Twin thread in this forum. Don't know how that affect the planned production of these units/boards.


----------



## Tom.W

We got burned pretty good but the ET2 should be back soon !


----------



## buttsplice

As soon as evil twin is back up, we'll get this started


----------



## rajdude

Does anyone have the bare PCBs/boards?

Wanna sell?


----------



## rajdude

Sorta OT but I HAVE to say it here.


After reading this thread I thought about trying out Gamma correction on my HTPC.


Boy-O-Boy !! I was surprised!

What a difference that control makes on the black levels and shadow details. I have been suffering with low shadow detail for almost an year and it was right below my nose!


I never tweaked gamma thinking that we are not supposed to touch the gamma controls. Now why did I get that thing in my mind? I think I read that somewhere here.


----------



## linecircle

I also tweak gamma to see more shadow detail. The problem with my situation, however, is not lost shadow detail, it's too much stray light hitting the screen and overwhelming it. So when I up gamma to make that shadow detail brighter, I lose some of the black blacks. Shadow detail in a bright scene is pretty 'grey', but starfields and such are still great. I'll have to fix the lighting situation some time...


----------



## Soapsuds

Raj....what video card are you using?????


----------



## rajdude

Quote:

Originally Posted by *Soapsuds*
Raj....what video card are you using?????


you'd be dissapointed with what I use  >>


Onboard video on a Recent Intel Motherboard.  


I do have a older nVidia MX440 but it does not have the horsepower hence I do not use it.



Sorry for hijacking your thread, tse


----------



## buttsplice

Since we're on the subject... when tse first mentioned this circuit and posted his gamma curve, I attempted to mimic the curve on my HTPC. I found a program called Calibration Tester that can read a custom gamma profile from a text file in a simple format. I figured out a rough approximation for tse's curve and used Excel to generate the numbers needed. Just load my custom file (attached) and you'll see that it does help shadows without washing out everything else, but I'm not sure how accurately it mimics the hardware version.

Calibration Tester 









 

tsecurve.txt 5.5966796875k . file


----------



## rajdude

Eric,

How does this utility+curve's performance compare with modifying the gamma curve using the video card's driver utility / display properties??


I notice that bottom left hand corner is elevated in tse's curve, whereas modifying gamma using vga card's utilities keeps that corve's bottom firmly in the corner of the graph.




-Rajiv


----------



## Chad N.

Would Toshiba's TA8696F gamma correction IC work for this application?

It seems this would be much cheaper/simpler.


I have been looking for a non-HTPC hardware gamma correction solution and stumbled on this thread. Since I don't have 5 posts yet, I cannot link to the datasheet. Do a search on google to find it.


----------



## buttsplice

 Datasheet 

Maybe. How much is that IC? It would lower the part count but the big ticket items are still there and I'm not sure that the gamma curve would be as customizable as it is with tse's design. I only glanced at the datasheet so I'm not sure how well it'd work but I don't see this part at any of the normal distributors so it's irrelevant till we see a price. Video IC's can be fairly expensive due to the bandwidth involved... do you have a distributor?


Raj: The curve I made is supposed to mimic tse's curve, which means it boosts the shadow details without washing out the upper end of the band. I hear you can do a similar thing with nVidia's newest drivers but I haven't tried. Every other driver I've seen will boost the lower end but also boosts the upper end considerably, which causes whites to be crushed and color saturation suffers. Just try them out on your monitor and you can get an idea of how they work. I find that darkish pics from a digital camera work well for this.


----------



## carpfisher

How do we get this text file into NVidias drivers?


----------



## buttsplice

Dunno, just use the utility


----------



## RGBHV

So Buttsplice,


When might you want/need beta testers ?? ;-)


----------



## linecircle

Interestingly, tse's curve is what I've settled on using after incremental experimentation with Powerstrip. I wanted blacks to be elevated but maintain a smooth but decreasing gain up to normal and high levels where they are unchanged.


Powerstrip colour correction settings:

Gamma 1.30

Brightness 70%

Contrast -30%

Temp 6500K


You can vary the values a bit to suit your preference of how much shadow detail to bring out.


----------



## Ericglo

linecircle,

And you would be wrong. tse's curve just bumps the bottom end without touching any other part of the curve. Plugging in 1.3 for gamma results in something entirely different. The goal was to boost the bottom end just enough to give shadow detail without effecting anything else. Scott has said that it would probably be beneficial for HTPCs as well. That being said it looks like there needs to be more testing on these software solutions.


Ericglo


----------



## linecircle

Yes, just boosting gamma to 1.3 does bump up the whole curve. Then brightness shifts the curve up even more, while contrast tilts the curve to correct the high end. Examining it more closely, I now see it is not tse's curve, but only an approximation. It'd be possible to do a better job using Nvidia control panel.


----------



## Chad N.

Anybody know of a distributer other than the usual Mouser, Digikey, etc that would stock Toshiba's TA8696F gamma correction IC?


----------



## tse

If I am reading the spec correctly (TA8696F) the bandwidth is only 4-5MHz.


----------



## buttsplice

Quote:

Originally Posted by *RGBHV*
So Buttsplice,


When might you want/need beta testers ?? ;-)
tse's board survived beta testing last fall... it's time to _build_ these things now! 


The twin is back up so let's coordinate an "intent to purchase" thread there then move on this before it gets hacked again 
Intent to Purchase thread


----------



## Tom.W

Hi Buttsplice,

How many preorders do you need before you decide you are ready to go thru with this ?


----------



## buttsplice

Orders are now being taken!  
Evil Twin order page


----------



## YONEXSP

Does someone want to try & mimic tse's curve in the NVidia Control Panel and create a ICC colour correction profile that can be imported into the NVidia control panel?


----------



## romberth

On color corrections, you go in advanced mode and create points on the curve to shape it like Tse's.


----------



## YONEXSP

All colours?


----------



## romberth

Yes, that's what I did. The thing is it's hard to shape the curve cause the nvidia window is so small, set your screen to 800x600 might make it easier.

Btw, it's just an attempt to mimic Tse's curve, not sure how accurate you can get...

Rom


----------



## YONEXSP

I also tried the Sharpness feature in the Nvidia control panel. It definately made the Playback in PowerDVD sharper


----------



## YONEXSP

The Nvidia control panel gives you thr reading for 'in' and 'out' cordinates. Surely the TSE curve as those values availbe? Then it would be easy to match them, any thoughts?


----------



## carpfisher

I've tried playing around with the gamma curve in nvidia's driver, and yes, it does affect the desktop, but the video window I have in the middle of the screen stays exactly the same. How could that be?


----------



## Mark_A_W

Sound like you are using the overlay to render the video - a completely different bit of hardware on the video card, not affected by the normal colour controls.


You need to use VMR9 to render the video.


----------



## YONEXSP

Or apply the Gamm achange to ALL, then it will affect the Overlay. Or put it in Advanced mode for overlay. Then manual adjsut points ont he curve, it will change the gamma for the overlay then.


----------



## M.D.

tse, you have PM.


A friend of mine has built a LMH1251 & LMH6739 based component to RGB converter. We want to add your circuit into it and design a new board. We would appreciate a lot if you could enlighten us.


Thank you.


----------



## Tom.W

 If anyone wants to order one of these please PM me ...


----------



## buttsplice

M.D., search for the old gamma thread that has schematics, gerbers, output graph, etc. Somebody else here was talking about integrating this circuit into a LMH1251 transcoder so you might dig them up too.


----------



## jtnfoley

Quote:

Originally Posted by *buttsplice*
M.D., search for the old gamma thread that has schematics, gerbers, output graph, etc. Somebody else here was talking about integrating this circuit into a LMH1251 transcoder so you might dig them up too. 
I was... I've got samples of the 1251 and 6739 and everything, but lately I seem to have no idea where I'm going or why I appear to be riding in a handbasket.


It was my hope to combine the 1251 and gamma circuit and fab a card small enough to "daughter" into an NEC ISS or Sony PC1271 switcher.


I had exchanged some PMs with another member regarding power supply flexability (to handle the voltages available in those two switchers) but that's about as far as I got.


Hopefully I'll be better able to "play" when [email protected] calm down.


----------



## WTS

Hi,


Yes there are going to probably be a number of products which will have the tse circuit integrated into the whole design. I'll be working with Moome on his newest offerings which will include the tse circuit in part and there is a very good possibility that there will be another tcoder or 2 coming out with it included as well.

It just seemed silly not to include it in new designs considering the amount of talk and the number of people wanting it in their systems.

So you'll beable to kill 2 or more birds with one stone so-to-speak by just waiting for these products to come available, which I don't think will be too long in coming.


----------



## Deja Vu

A question for those using an HTPC and the Nvida 6600 video card. I am using Theatertek and with my old ATI card I had gamma corection with the TT settings. With the Nvida card I've lost gamma in TT. I have put it into advanced mode in overlay and changed the gamma; however, it is not affecting the image at all. I need help!


Thanks,


Grant


----------



## YONEXSP

Sounds like you are using VMR9 with your 6600 but were using overlay with the ATI. In VMR9 Renderless no Gamma is available in TT. Youy should adjust the gamma for the desktop for VMR9 renderless mode to affect TT


----------



## Deja Vu

Yonexsp,


Thanks for the help (your advice did the trick). I've got it working now.


Cheers,


Grant


----------



## M.D.

Thanks, buttsplice & jtnfoley. I did dig up something. And thanks to tse's suggestion as well.


Will let you people know when we successfully integrate the two.


----------



## Deja Vu

O.K. I've been experimenting with the Nvida 6600 and gamma correction. Here are some of my thoughts about a couple of things that have been discussed here.


1) Tse's gamma correction does effect the gamma curve globally, albeit indirectly. My understanding is that what we're doing here is to use gamma changes to boost the bottom end of the video so that when we lower the black level (brightness control) to obtain full fade to black we retain shadow detail. If you look at Tse's gamma curve it appears to boost gamma at the bottom and then quickly come back to intergrate with the linear line at the top; however, as soon as you start to lower your black level the entire curve is effected, rather dramatically with the bottom end of the curve moving to the right along the x axis (horizontal line) and the top end dropping and curving more to the right, away from the y axis (vertical line). The Nvida 6600 has a graph for settings (gamma, brightness and contrast) that allows the user to experiment with custom setting and see how these three intreact. A change to one effects the others - they are not independent of one another. As you lower brightness (black level) the lowest point of the curve moves horizontally to the right along the x axis (horizontal line) and away from where the x and y axis meet one another. The top end of the curve moves downward. I mimiced Tse's curve, as best I could, and found that you had to really drop brightness dramatically to obtain a full fade to black. I also tried a similar curve, but this time with the curve beginning along the x axis (horizontal line) instead of originating along the y axis just above the point where the x and y axis meet (Tse's curve) with an initially slightly steeper rise. Obviously you don't need the same changes to black level to obtain full fade to black. This brings me to my next point.


2) Many people on this forum know infinitely more about encoding than I do and no doubt will correct some of my assumptions here, if I am totally out to lunch. Anyway, it is my understanding that source material is encoded with intensities starting at 0 (black) and rising in increments of one until we arrive at 255 (white). I am not sure about this, however, if a DVD, for example, is encoded using 8 for black instead of 0 then we have a situation where there is some gain for this particular "black" and what we see on a CRT is a dark greyish glow. If we lower black level this "glow" fades to total black but the consequence is that we crush shadow detail and therefore need to correct gamma in order to retain both the full fade to black and shadow detail. I think what we're doing when we lower the black level is that we're moving the bottom of the gamma curve to the right along the x axis (horizontal line) so that rather than 0 being black, 8, for example, (in the 0 to 255 scale) is now absolute black and we get our full fade to black and if we have increased the curve (gamma correction) at the bottom end we can retain shadow detail(?). If something was encoded with 10 being black then we might have to again lower our black level by a notch or so to retain full fade to black (in other words fudge it a bit).


What I am hoping is that someone with some knowledge in this area will step in and either correct me or discuss this in more detail.


Personally I feel that gamma correction, although not a panacea for some of CRTs shortcomings, makes the most dramatic improvement to image dynamics that I have seen so far. Many who have converted to digital complained that their CRTs were dull and lifeless and couldn't do a full fade to black and retain shadow detail. Gamma correction, IMO, along with room calibration and screen choice, adds vitality and dynamics big time to what a CRT can do giving it an unrivaled image (IMO), at least for now.


Cheers,


Grant


----------



## tbrunet

Quote:

Originally Posted by *Deja Vu*
if a DVD, for example, is encoded using 8 for black instead of 0
Luminance signal:

220 quantization levels with the black level corresponding to level 16 and the peak white level corresponding to level 235. The signal level may occasionally excurse beyond level 235


I have measured nominal DVD luminance levels and "NONE" are using levels (1-254), FWIW (0 & 255) are not possible video levels. In fact the so called WTW/BTB

information excursion i.e. measured 14-237, these were brief detail "image filter ring" or overshoot, they represented +/- 2 levels, but not sustained luminance "black" or "peak white".


----------



## tbrunet

Quote:

Originally Posted by *Deja Vu*
source material is encoded with intensities starting at 0 (black) and rising in increments of one until we arrive at 255 (white). I am not sure about this, however, if a DVD, for example, is encoded using 8 for black instead of 0
Luminance signal:

220 quantization levels with the black level corresponding to level 16 and the peak white level corresponding to level 235. The signal level may occasionally excurse beyond level 235


I have measured nominal DVD luminance levels and "NONE" are using levels (1-254), FWIW (0 & 255) are not possible video levels. In fact the so called WTW/BTB

information excursion i.e. measured 14-237, these were brief detail "image filter ring" or overshoot, they represented +/- 2 levels, but not sustained luminance "black" or "peak white".


----------



## Deja Vu

Tbrunet,


Thanks for the information and for correcting me. Can you give an example of what a "typical" DVD is encoded at for the "black" level (I would really like to know so I have an idea of what we're dealing with). Is HD different (I am assuming that it is)?


I am going to mimic Tse's curve again and this time I'll run the upper end above and parallel to the upper end of the linear line so when I drop the black level and the curve shifts to the right it will hopefully overlap the original upper end of the linear line thus keeping the top part stable with only the bottom end being effected by the gamma correction.


Cheers,


Grant


----------



## tbrunet

Quote:

Originally Posted by *Deja Vu*
Can you give an example of what a "typical" DVD is encoded at for the "black" level (I would really like to know so I have an idea of what we're dealing with). Is HD different?
I think the new HD/DVD format will still be 8 bit, just increased resolution i.e.


HD & SD Reference Black 8 bit video/DVD (Y) = 16

HD & SD Reference White 8 bit video/DVD (Y) = 235


*Reference Blk-Wht 10 bit video 64-940

*Just to be clear  I'm referring to the data on the DVD "disc", how one expands these levels to PC/RGB [0-256] is a rather provocative SM!


(H)1280 x (V)720 HD resolution

(H)1920 x (V)1080 HD resolution


*compared to SD, DVD I think is 480 vertical lines


----------



## Ericglo

It may be helpful for everyone to be on the same page regarding gamma. This article should do that. 


Grant,

Scott believes that it is not possible to mimic his curve with a computer at this point in time. I am not sure if he has tested his card with a computer, but he did tell me that he thought it would be beneficial for computer users.


Ericglo


----------



## darinp2

Quote:

Originally Posted by *Deja Vu*
Can you give an example of what a "typical" DVD is encoded at for the "black" level (I would really like to know so I have an idea of what we're dealing with).
It is supposed to be level 16 in 8 bit space, but as we have discussed some blackouts get encoded higher than 16. Somebody told me that when the monitors used for mastering are setup with the SMPTE colorbars pattern that video 16 actually ends up being just slightly brighter than levels below it. I think it would be best if blackouts got encoded at something low like 5 to make things easier, but it doesn't seem like they do. With a PC you might be able to go change a LUT so that 16s get remapped to 5s and see how that works. Then you wouldn't need to change the gamma at 17, 18, 19, etc. in order for all 16s to blackout and hold it.


--Darin


----------



## Deja Vu

If you look at Buttsplice's graph (trying to emulate Tse's gamma curve) you'll notice that the curve starts on the vertical axis (slightly above where the vertical and horizontal axis meet) and not at the point where the two actually meet. I customized my graph to look like this and found that it was not possible (at least for me) to retain any full fade to blacks whatsoever; however, if I stated the curve on the horizontal axis slightly in from where the two meet then it was quite easy to obtain full fade to black with other scenes showing more or less detail depending on the steepness of the curve. I am somewhat skeptical that the gamma curves as depicted on page 14 of this thread accurately simulate Tse's actual gamma curve. Anyway, just my two cents.


Cheers,


Grant


----------



## YONEXSP

Deja Vu, can you email me your Gamma file from Nvidia?


----------



## buttsplice

Back to the boards... I'm going to be building these this weekend and I'll have 3 extras so PM me if you're interested in them.


----------



## buttsplice

I still have one left if anybody needs one


----------



## WTS

Hi,


So I hope people are going to report on what they think of the circuit and whether they think it improved the pic after they get them.


----------



## GlenF

Buttman!

Can you PM me a price and shipping to Australia? I am running a momitsu with a PG+ so it sounds like a good idea to get one of these I think?


----------



## buttsplice

I'm fresh out of boards from the first run but I will entertain a second run if there's enough interest.


I coordinated the build over at "the other site" and folks are starting to post their impressions of the boards I just sent out. I'd give you a link but AVS filters out the name... see if this works:
http://www.4**0p.dk/eviltwin/forum_p...195&PN=1&TPN=1 


AVS filters out the site's domain so replace the stars with zeros.


----------



## dominical2

So far tse's design is working as planned !


----------



## madpoet

I am really liking the board so far... need to get my system dialed in now!


----------



## tse

A .pcb file of a single board as requested.


Can't upload .zip files anymore????


Rename the file to rev01.zip to use.

 

rev01.txt 19.470703125k . file


----------



## Ile

Quote:

Originally Posted by *Deja Vu*
If you look at Buttsplice's graph (trying to emulate Tse's gamma curve) you'll notice that the curve starts on the vertical axis (slightly above where the vertical and horizontal axis meet) and not at the point where the two actually meet. I customized my graph to look like this and found that it was not possible (at least for me) to retain any full fade to blacks whatsoever; however, if I stated the curve on the horizontal axis slightly in from where the two meet then it was quite easy to obtain full fade to black with other scenes showing more or less detail depending on the steepness of the curve. I am somewhat skeptical that the gamma curves as depicted on page 14 of this thread accurately simulate Tse's actual gamma curve. Anyway, just my two cents.


Cheers,


Grant
I have scoped both and it's possible to do same kind correction using Nvidia driver. Exept Nvidia can't boost signal over 700mV, but it isn't needed anyway.


Digital correction gives possibilities to do correction freer, so why should we simulate constricted analog correction?


----------



## picree

Ile-maybe some here are concluding that the tse curves approach an ideal curve for a CRT projection system. I know tse played with different curves to arrive at the one used in the board. I think this work also was born from a bigger effort at improving CRT-based projection system limitations (crushed blacks)...so there were a lot of other hours and tests behind this effort.


I built two of these boards last year and have been thoroughly pleased with the results. Neither my scaler (Crystal Image 2.0) nor my projector (BG808) have any ability to create a gamma curve and I don't have a HTPC. Without the tse boards all I can do is shift G2's, cutoffs, and gains...all of which only effect the gamma curve linearly.


My BG808 looks nothing like my neighbors G90 but the tse card helps it get closer and definitely helps me get the most out of the 808. Dollar for dollar it's a good deal.


My 2 cents.


----------



## buttsplice

See the attached image for an actual input-output comparison I did on tse's board. It's only a 16-step pattern so you don't get the full effect but step #0 is at 0V on both input and output. If somebody can send me a full black-to-white horizontal sweep in 4:3 format I will post the results again, which will be a line instead of a staircase. I'll also attach the image I used in case you have no idea what I'm talking about


----------



## Ericglo

Hey spice, can you post the 16stair without the gamma attached?


Ericglo


----------



## Chris Bigos

The top pic *IS* the 16 stair without gamma - isn't it???


----------



## tse

The rev 01 board files with just one PCB.

http://www.avsforum.com/avs-vb/showt...&post6295830 


Is the parts list. Change the LT1213 to MC33077P to save some bucks. Add three 220K 1/8W resistors.


Change the attached file extension to .zip to use.

 

AVS_GAM_DCR_rev01.doc 191.27734375k . file


----------



## Ile

Quote:

Originally Posted by *buttsplice*
See the attached image for an actual input-output comparison I did on tse's board. It's only a 16-step pattern so you don't get the full effect but step #0 is at 0V on both input and output. If somebody can send me a full black-to-white horizontal sweep in 4:3 format I will post the results again, which will be a line instead of a staircase. I'll also attach the image I used in case you have no idea what I'm talking about 
 Here is my input-output comparison using black to white sweep+5%steps from DVE. Step two is video black.


I had wrong AR in TT2, so few last mV are missing.


----------



## Chad N.

Could someone please post before and after screenshots of something like a movie scene still?


----------



## picree

I don't think it would show you much. How do you take a picture of better blacks?


Before the tse card: when I set my black levels such that I didn't crush blacks there was a noticable grayness to the screen when a movie would switch from scene to scene.


Now? With the tse card I can avoid crushed blacks but when a movie switches between scenes? Black is black baby! It makes me grin every time! What else? Colors look a little deeper and more vivid...not that a BG808 will look like a G90...it won't. But certainly much better.


If you don't have a HTPC and you have a projector like an 808 (w/ no gamma correction) then this is a great upgrade! Worth the money. I built two. Now a G90 doesn't seem to benefit much (my neighbor). It's too good to begin with (my opinion) but the 808's, 1208's, 1209's (or any comparable w/o input gamma correction) look better.


My 2 cents.


----------



## JaniH

Quote:

Originally Posted by *Chad N.*
Could someone please post before and after screenshots of something like a movie scene still?
Here's one:

Without and with gamma correction circuit. Projector is a BD801s. Brightness was adjusted so that shadow detail would be roughly the same and contrast was set by eye, so this isn't even close to exact science. But you can clearly see that the black is more washed out without the gamma correction.


However on high APL scenes the gamma correction circuit provided a worse picture than without it with my projector. Colors were clearly washed out and muted, like looking through a filter of some kind.


----------



## dominical2

I also have tse's card . I like the low end boost but I need to adjust the contrast down a bit to compensate for brighter scenes.


----------



## carpfisher

I would say that the scope plot in post #452 doesn't look good - because the white is boosted too much. I thought that the point of the design was that the top curve meets the bottom one at peak white. The response shown will surely have people turning their brightness down, to avoid crushing whites, which will affect the bottom end as well, maybe negating the benefit?


Does the design need to be tweaked slightly?


----------



## tse

Quote:

Originally Posted by *Ile*
Here is my input-output comparison using black to white sweep+5%steps from DVE. Step two is video black.


I had wrong AR in TT2, so few last mV are missing. 
The scope image is of the gamma bd in and out? I know you were experimenting with PC video card gamma, also.


Where are the little horizontal "markers" coming from?


----------



## tse

Quote:

Originally Posted by *dominical2*
I also have tse's card . I like the low end boost but I need to adjust the brightness down a bit to compensate for brighter scenes.
Try adjusting the projector brightness for good shadow detail with a very dim scene then adjust the contrast on a very bright scene.


----------



## tse

Quote:

Originally Posted by *JaniH*
Here's one:

Without and with gamma correction circuit. Projector is a BD801s. Brightness was adjusted so that shadow detail would be roughly the same and contrast was set by eye, so this isn't even close to exact science. But you can clearly see that the black is more washed out without the gamma correction.


However on high APL scenes the gamma correction circuit provided a worse picture than without it with my projector. Colors were clearly washed out and muted, like looking through a filter of some kind.


See the above post. The whole idea of the card is to increase the brightness of dim scenes to enhance the shadow detail. If the bright scenes are washing out turn down the contrast.


----------



## JaniH

Quote:

Originally Posted by *tse*
If the bright scenes are washing out turn down the contrast.
It wasn't about contrast setting - color saturation was lost regardless of contrast setting (yes, I checked the color saturation adjustment in my scaler with AVIA). All peak white information was still visible, so my whites weren't washed out, just colors were a lot duller. Setting the RGB driver of the projector to match the 1.1V input voltage could've helped, but unfortunately I hadn't time to try this.


My friend tried the same GC unit with his projectors. With Barco 500 colors were actually improved but with Panasonic 1085 results were the same as with my pj - muted colors. A fast conclusion would be that this box is better suited for some projectors than others, or there's something fishy with the unit we're testing. I'm not trying to bash your great work, just wondering what happened with my testing.


----------



## tse

You are using RGB input? Not component? The output from the gamma box goes to the projector input. Turn the pot full clockwise, not like the schematic says. Just want to make sure there is no misunderstanding about using the gamma box.


JaniH quote "Setting the RGB driver of the projector to match the 1.1V input voltage could've helped, but unfortunately I hadn't time to try this."


What does 1.1V input voltage mean?


----------



## Chris Bigos

I read it that 1.1 volt is coming out of the card and into the PJ. Didn't someone have a component or something in the wrong way round in the early days (maybe Picree?) that caused the o/p to be 1.X volts?


----------



## Ile

Quote:

Originally Posted by *tse*
The scope image is of the gamma bd in and out? I know you were experimenting with PC video card gamma, also.


Where are the little horizontal "markers" coming from?
That picture is from gamma box I tested.

1. channel, signal in

2. channel, signal out


Horizontal markers are coming from testpattern 5% gray steps, 5% below black to 5% above white. Testpattern also have sweep from black to white.


----------



## JaniH

Quote:

Originally Posted by *tse*
You are using RGB input? Not component? The output from the gamma box goes to the projector input.
RGBH from scaler (VP30) to GC box and there to projector, V sync goes directly from scaler to pj. RGB color space.

Quote:

What does 1.1V input voltage mean?
That the box is outputting 1.1V instead of 0.7V, if I've understood correctly. Sorry if I was unclear, I meant that the input of the pj gets 1.1V, not the input of the GC box.


I haven't got the box anymore so I can't do additional testing. Pots were set by Ile as he was the previous tester, I didn't touch them.


----------



## Ile

Quote:

Originally Posted by *carpfisher*
I would say that the scope plot in post #452 doesn't look good - because the white is boosted too much. I thought that the point of the design was that the top curve meets the bottom one at peak white. The response shown will surely have people turning their brightness down, to avoid crushing whites, which will affect the bottom end as well, maybe negating the benefit?


Does the design need to be tweaked slightly?
I think those curves can't be compared before video black levels are balanced. That's because box also boost below black information.


After video black levels are balanced, both have pretty same peak white levels. Video black is second horizontal marker...


JaniH as you can see from my picture, box was outputting pretty close 700 mV.


----------



## tse

The output should equal the input when the input is 0.7Vpp with some full white content. Small changes to the resistor in R2 spot can adjust for perfect gain = 1.


Change all three with same value. Small changes only.


Pots will probably cause bandwidth problems, not recommended.


Changes should not be attempted unless using scope to monitor results. Use of precise 0.7V video input required.


Etc., ect.


Ile,


Now I understand what the horizontal markers are. I don't know why I didn't see that at first.


Scott


----------



## zamboniman

How good would this circuit be at driving a long line run?


I have a card built by buttsplice and would like to have it applied to all sources.


I'm currently using an NEC switcher that has about 30' or so of coax rgb line to the projector.


I'm on the fence between what seems better but harder to implement or the easy road.


Would be easy to put the card in a case located at the rack but then it would be driving all that line... Or it could go at the projector but that creates a mounting issue..


Any thoughts?


----------



## tse

Should be ok if it is decent quality coax.


----------



## PAW

zamboniman


The NEC ISS switcher can boost the output. There's a rotary switch on the output card. However, this is for all inputs. You can also boost the RGB gain on an individual input card via the buttons on the front.


----------



## zamboniman

PAW,

Right I know that.... the NEC ISS is a great line driver. That's why I was hesitant about putting the gamma card right after it in the signal chain. I didn't want to eliminate the benefit of it's drive circuitry. The only option I could see to get all inputs through the gamma circuit would be to put it at the projector itself.


For now I'll probably just put it at the equipment rack after the switcher and see how it looks for awhile. By doing this I won't be able to use the NEC boosting ability. It's probably not necessary anyway with my line though.


----------



## PAW

zamboniman

So, putting the gamma card AFTER the ISS will niegate any boost the ISS added?


----------



## zamboniman

Well you wouldn't want to overdrive the card.. If you put it right after the ISS before the long line run and were running the ISS with some boost you could very well be overdriving the card and doing more picture image harm than good. So running the ISS without the boost to match the input of the card which is located right next to it.. The card itself is left to be the buffering interface to the long coax run.


That's why I was thinking about putting it at the projector end of the cable. So I could use the ISS to provide the correct signal levels after the cable run at the proj. But insert the gamma correction on that signal right at the projector.


In the end the differences in picture are probably not enough to worry as long as nothing is overdriven, but that said you have to remember that you can't just boost the signal with the ISS like a crazy man when there is another component right inline with it.


Probably don't even need any boost for the length of the cable I'm using.


----------



## Prehjan

Quote:

Originally Posted by *VideoGrabber*
> _I already included it into his design, but only as part of the tcoder circuit._ 
_So moome's transcoder has tse's gamma circuit. That is good to know._


----------



## WTS

Hi,


None of Moome's cards have it yet.


----------



## PAW

Quote:

Originally Posted by *WTS*
Hi,


None of Moome's cards have it yet.
Moome's NEC ISS card is suppose to. When it's released.


----------



## WTS

Well that is yet to be finalized.


----------



## Prehjan

I would be interested in the NEC 6010/20 card if someone were to sell me an extra ISS6010/20 they might have?

I guess I can check on ebay or videogon tonight...


Martin


----------



## 1031

Quote:

Originally Posted by *tse*
The output should equal the input when the input is 0.7Vpp with some full white content. Small changes to the resistor in R2 spot can adjust for perfect gain = 1.


Change all three with same value. Small changes only.


Pots will probably cause bandwidth problems, not recommended.


Changes should not be attempted unless using scope to monitor results. Use of precise 0.7V video input required.


Etc., ect.


Ile,


Now I understand what the horizontal markers are. I don't know why I didn't see that at first.


Scott
OK i tested that resistor value change to make get output back to 0.7v..(mine was that 1.1 volt also) that 510ohm must be changed to 1.2kohm!! to get that 0.7 volt output ? I tested that with videosignalgen. and digital oscilloscope. and yes i didint forget those 75ohm terminationresistors. Ok this corrector is not"standard" model, i use little more "boost" for correction( instead those R1 2.4kohm i use 1.5kohm to get gammacurve more suitable for my sony 1272)


Bye the way TSE. Can i "move" that bendingpoint (of that correction curve) lower just bye changin those sd101a diodes to sd101c (forward voltage drop for sd101 a is 0.41 and for sd101C it is 0.39volts)?


----------



## tse

1031,


Are there other changes than R1=1.5K? That should not make that big of a difference from original. The attachment shows input vs output with R1=2.4K and R1=1.5K.


Only the peak to peak value is important. This circuit will shift the DC level down where "black" is slightly negative but that doesn't matter as the projector's input is AC coupled and the DC restore takes place internally.


Scott


----------



## tse

If there is going to be experimentation with any discrete circuit I would recommend using the little pin sockets that are part of some IC DIP sockets. They add little parasitics and let you change components easily. Check the attachment.


Scott


----------



## 1031

Quote:

Originally Posted by *tse*
1031,


Are there other changes than R1=1.5K? That should not make that big of a difference from original. The attachment shows input vs output with R1=2.4K and R1=1.5K.
No. Thats only difference.

I made two correctors and second one is for testing purposes. And that second one was that same that JaniH and ILE tested. And that second was "original desing" they also noticed that outputlevel was little too strong. On my sony that was not problem because there is trimmers at inputcard for signal level correction..

I have nothing to complain, Im very happy with that gammacorrector.. But some others has noticed that "boost"...


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