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Anyone know how to build a "VGA out" to a "component in" box?
Frigo:
More precisely: VGA ---> BOX ---> Component ---> TV.
Diagrams, instructions, pity; I'll take anything. I'm moderately competent with electronics, but can't read a diagram without some help. Thanks!
BobA:
Depends on your video card. Some ATI cards just need the proper adapter that will not work on other video cards.
Frigo:
I was actually thinking of pulling R,G,B,Sync,Ground, etc signals from a video encoder chip like the CXA1145 (common in older video game consoles) and feed it through some sort of circuit to convert it to component.
MonMotha:
There are two things you need to handle: colorspace, and sync. Remember, RGB (aka "VGA") is a component video format, it's just in a different colorspace than what most TVs with "component" inputs expect.
Colorspace is just a bunch of analog electronics. Basically, you need some summers/differencers to handle the RGB to YPbPr matrix. http://circuits.linear.com/158 is a handy app note from LT that might work. There are several other ways of doing it, too.
The other difference is sync. PC outputs have TTL level, separate sync. YPbPr has composite sync on Y. An XOR gate (or several combined with some suitably sized RC networks for auto-polarity handling) can get composite sync from the separate syncs. Then you can use a transistor or similar to dump sync onto the Y line.
All that said, why build one? You can buy a pre-made one for like $20-40, and you won't have to futz with it.
You WILL need to feed the box video timed suitably for your TV. 640x480 "VGA" is compatible with 480p aka "EDTV". If you want standard def, you'll have to output either 320x240p or 640x480i (interlaced). Various methods can get this from your PC e.g. Soft15kHz if you run Windows or some suitably chosen modelines on Linux. HD modes will usually work, too, so you have have 720p, 1080i, or even 1080p if your TV supports it. Check compatibility with your desired resolution on any box you buy.
You can't use a CXA1145 for this. It does not expose the unmodulated chroma components (which would be I/U and V/Q, very closely Pb and Pr) outside the chip. It just has the modulated chroma signal used for S-Video (though the luma "Y" signal is present). FWIW, CXA1145s can be hard to find now. Analog Devices makes a similar chip with P/N AD725. Rohm also makes one that's used on the popular cheap China-made "RGB to S-Video" adapters.
Frigo:
--- Quote from: MonMotha on October 29, 2010, 03:25:17 am ---There are two things you need to handle: colorspace, and sync. Remember, RGB (aka "VGA") is a component video format, it's just in a different colorspace than what most TVs with "component" inputs expect.
Colorspace is just a bunch of analog electronics. Basically, you need some summers/differencers to handle the RGB to YPbPr matrix. http://circuits.linear.com/158 is a handy app note from LT that might work. There are several other ways of doing it, too.
The other difference is sync. PC outputs have TTL level, separate sync. YPbPr has composite sync on Y. An XOR gate (or several combined with some suitably sized RC networks for auto-polarity handling) can get composite sync from the separate syncs. Then you can use a transistor or similar to dump sync onto the Y line.
All that said, why build one? You can buy a pre-made one for like $20-40, and you won't have to futz with it.
You WILL need to feed the box video timed suitably for your TV. 640x480 "VGA" is compatible with 480p aka "EDTV". If you want standard def, you'll have to output either 320x240p or 640x480i (interlaced). Various methods can get this from your PC e.g. Soft15kHz if you run Windows or some suitably chosen modelines on Linux. HD modes will usually work, too, so you have have 720p, 1080i, or even 1080p if your TV supports it. Check compatibility with your desired resolution on any box you buy.
You can't use a CXA1145 for this. It does not expose the unmodulated chroma components (which would be I/U and V/Q, very closely Pb and Pr) outside the chip. It just has the modulated chroma signal used for S-Video (though the luma "Y" signal is present). FWIW, CXA1145s can be hard to find now. Analog Devices makes a similar chip with P/N AD725. Rohm also makes one that's used on the popular cheap China-made "RGB to S-Video" adapters.
--- End quote ---
Wow, that sounds like a lot more than I'm ready for. Isn't there any way to pull the signals from the encoder chip and feed it to a pre-made box without having to go through the hassle of getting a scart cable/converter (which isn't in my budget at the moment)? Also, where would one go to find a pre made box if this were possible?
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