Convert Composite to S-Video

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Hi Gurus over there !

Using Tomi Engdahl's solution (470 pf cap connecting C to Y) to connect the RCA output of my VidCam to the S-Video socket in my Capture Card I get the video ok but the picture shows wavy lines like serrations across the screen - a search in Google indicates this is common with such simple solution.

Anyway I am looking for a circuit to split the composite video so that I can have the pleasure to build one. I would rather not go for chips like AD725 but require a circuit that uses basic components.

If one of you know of such a circuit or have the link for one, will you please let me have it?

Thanks in advance for your time and attention.

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Sandy Archer
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Ardent
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What happens if you

1) build it in a small shielded enclosure using shielded cables

2) try it without the cap, so that you are driving only the luma? Does this at least get rid of the interference?

For common consumer Brooktree/Conexant/Fusion/whatever type chip video capture cards, the luma half of the S video in (if it is implemented) is connected to a pin (multiplexer input actually) that is also able to receive composite video, while the chroma is fed into a seperate pin. So if your card has one of these, all you might need to do is set the approriate option to the driver.

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cs_posting

You need to remove the chroma from the composite feed . You have chroma info on both C and Y, so I suggest that they are being mixed, so you get patterning. Maybe a lump of 75 ohm coax, on the Y sig, unterminated, will notch out your subcarrier. Cant remember the correct length...

formatting link

martin

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martin griffith

Yes, that seems to be obvious route. I have seen the above page and will try to work out a filter.

And thank you very much for the lead. Thanks to the others also who tried to help me.

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Sandy Archer
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Ardent

Whatever for? Simply filtering the video to separate chroma/luma is a 'trap'. This is what is already in the cheapest TV sets. To do it right (as in it actually looks better) requires a 3 line adaptive comb filter. These are already in the better grade TV sets. So again, what for?

I think Motorola had a digital 3 line comb IC 10+ years ago. I believe it needed sync and 4x subcarrier to work.

GG

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Glenn Gundlach

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