On Nov 5, 11:23 am, Sam Goldwasser wrote:
I've seen a number of ways of doing this.

* Small capacitor from C to Y. Around 470 pF seems to be popular and works
relatively well. But there seems to be excessive color noise compared
to using the composite output of the same source (which presumably had to
do the same conversion). Increasing the cap value decreases color noise
but smears the picture.

* Direct connection from C to Y. Apparently, some cheap cables do this
(based on an ohmmeter, unless there is something else in there that
doesn't show up as a cap or resistor!). Works well on some sources
with decent resolution and minimal color noise, won't even sync on others.

* Rs in addition to the cap, but reduces video level.

* Active approaches?

So, is there an optimal conversion scheme???

Thanks.

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Truly no need for any active circuitry. The Bosch encoder from the mid
'80s used passive mixing and was a broadcast product. Capacitor
technique preferred.

GG