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Kilrah

Video AC coupling?

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I'm running into a problem with 2 pretty popular video devices. I have a set of video goggles, and an Archos AV recorder. I know soneone who would want to watch the videos that are on the recorder with the headset. Problem, the headset doesn't display anything, apart from a split second when both have just been connected together.

I've started by checking the Archos' video output, to find that it is of correct level, but DC-coupled, that is the sync pulses are at 0V instead of being negative. That apparently disturbs the goggles, where some other displays work. Normally devices should have coupling capacitors on both input and output, so even if one doesn't have it it will still work. But here it seems that both manufacturers have omitted them, and here comes the trouble.

I was planning on making a small cinch-cinch coupler that would include the decoupling cap, but can't seem to find the correct value to get a clean signal. Would having it in the middle of the line and not at an end be a problem, or would a specific value work better?

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470uF provides good sync fidelity. If space is a problem, 220uF is a second choice.

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