build your own RGB to component video converter

[nick3092]

I noticed the slide show URL jumped around to certain numbers in the URL. If you take the URL and put in the missing numbers, you get the missing pictures.

[Chilly Willy]

Sync is derived from the luminace signal...

Which is derived from the R/G/B... I'm talking about the ORIGINAL sync source. Sync-on-green is a semi-standard for RGB ports, but many monitors don't take SOG. That was a major issue with the Sony RGB cable for the PS2 - it required a monitor to support SOG.

I was remarking that since there was no composite sync or h/v sync inputs, the circuit MUST be SOG.

[TmEE]

oh.... well, all european RGB outputting devices have sync in composhit signal, or luminance. MD and some other devices use a separate sync, but composite is as good.

[Chilly Willy]

oh.... well, all european RGB outputting devices have sync in composhit signal, or luminance. MD and some other devices use a separate sync, but composite is as good.

I don't think you quite get what I mean yet. Look at the converter box - there are only three inputs: Red, Green, and Blue. There is no composite input. Using the composite defeats the purpose of using the RGB. Since the composite isn't used, you can't use the sync that's part of the composite. Since the only three inputs are Red/Green/Blue, one of them MUST be carrying the sync. The "standard" is to put the sync on the Green line.

I hope that clears up the confusion.

[sonictails]

I am. I used to use an RGB cable with my setup, and I miss the high quality display. Just from looking at the schematic, I assume this uses sync-on-green. Most RGB to YPbPr schematics I've seen assume the sync to be separate.

Alrighty. I'll keep you posted.

[TmEE]

I don't think you quite get what I mean yet. Look at the converter box - there are only three inputs: Red, Green, and Blue. There is no composite input. Using the composite defeats the purpose of using the RGB. Since the composite isn't used, you can't use the sync that's part of the composite. Since the only three inputs are Red/Green/Blue, one of them MUST be carrying the sync. The "standard" is to put the sync on the Green line.

I hope that clears up the confusion.

I did not pay attention to the schematic at all ...
This seems to get its sync from the green.... I have no devices that accept SoG...

[Chilly Willy]

I did not pay attention to the schematic at all ...
This seems to get its sync from the green.... I have no devices that accept SoG...

Yeah, but this is changed into YPrPb, so it won't matter. The sync will end up on the Y. The only reason I mentioned it is in case someone tries to hook this to something like an Amiga where you DON'T have SoG, it won't get a sync signal. You'd have to alter the device to work with separate sync sources.

[TmEE]

You only need one transistor and a resistor or 2 to create SoG environment for the converter...

[Chilly Willy]

After looking at replies on other threads, I think our discussion about SoG is relevant. I don't think the SEGA does it - it has a composite sync line it uses instead. So this box will have to be modified with another input for the sync which will need to be added to the Y signal as TmEE mentioned.

[David J.]

War2thegrave, when I come back to Watertown, I can show you my SCART RGB -> Component Transcoder if you like?

[tomaitheous]

I gonna build this device this month. Or rather, a device like this. This one has video amps, IIRC. The RGB coming out of the Genesis 'port' is already amp' to 0-0.7v range, AFAIK. So it doesn't need that part of the circuit. It's just leaves a matter of applying:

Y = 0.299*R + 0.587*G + 0.114*B + 0
Cb = -0.169*R - 0.331*G + 0.499*B + 128
Cr = 0.499*R - 0.418*G - 0.0813*B + 128

In the analog domain, with some resistor logic. And then putting composite sync on Y or Green after the transform.

[atnguyen]

Thanks. I also do not know how to covert it.

[mcurkman]

Why don't the photos on the original post work anymore?

[akaviolence]

I gonna build this device this month. Or rather, a device like this.

Have you gotten anywhere with this yet?
What circuit are you using?
I'm anxious to do one, but the elm-chan circuit isn't working for me...

[villahed94]

Have you gotten anywhere with this yet?
What circuit are you using?
I'm anxious to do one, but the elm-chan circuit isn't working for me...

Really, have you done it properly? Because that´s the one i´m going to do for my genesis in 2 months or so.