DIY Composite video signal limiter?

Hello everyone !

I’m sorry if it’s a very noob question, but here it is: I am quite new to video synthesis, for now I’m only working with a few modules with some composite video (Syntonie CBV001, CVB002 + Reverse Landfill Matrix Mixer, LZX Castle Series + camera), but when I make some “heavy” processing on the image, my screen or video projector are getting often out of sync (of course this is not the case with my CTR, but I read something about those to be more stable with analog signals).
To prevent that, I was wondering if there is a circuit that can input the composite signal, and limit it to the range of 0v - +0.7v, so that the signal “just” gets clipped and the image should be more stable ?
Or am I missing something and that wouldn’t work ?

Composite sync goes 300mV below “black” level (which is 0V if the white level is +0.7V) and above +0.7V (chroma waveforms) so the clipping you need is slightly more involved.

You could very likely use one of my DIY composite-to-eurorack bidirectional converters (1IF InterFace – Visible Signals) plus a ‘Wrangler’ video voltage processor module (Wrangler – Visible Signals) to achieve pretty-much your desired outcome (the Wrangler has an 0-1V clipped output). To retain the sync portion of the signal through the clipper output use the Wrangler voltage offset control to increase the output by +0.3V (most display devices will work perfectly fine with a small DC offset). You’ll probably still lose a bit of chroma on bright portions of the image though.

But then again, what encoder are you using? Most encoders will already output very stable and in-spec composite signals. The CBV001 is capable of quite some strong glitches, though - your best bet there is to use an external mixer with a tolerant TBC built-in (like the venerable WJ-AVE5 etc etc).

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It depends on what the issue is. Unless you’ve measured it, I’m not convinced that the problem is that your signals are going out of the voltage limits.

Some devices “circuit bend” or mess with the timing of your signals. CRT’s tend to deal with this beautifully, but digital displays, recorders and projectors can have problems with it.

How are you getting signals into your castles? You might want to describe the signal flow of a specific patch that is causing problems.

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Get an old broadcast tbc.

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