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Discussion Starter · #1 ·
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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Discussion Starter · #2 ·
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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Now how does that saying go "Build it and they will come."
 

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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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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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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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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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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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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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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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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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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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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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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. I’ve not seen it spec’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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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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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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Discussion Starter · #20 ·
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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