OK, I’m in the process of making this. I could use a svelte little B&W encoder as well.
I found this sync insertion circuit (below). It appears to be using an op-amp like a switch by powering it on and off with a sync pulse, allowing the sync signal to pass during the blanking interval. Then it occurred to me the signal is blanked already in the C2 circuit.
So far my circuit is one channel from the C2 schematic, up to the blanking switch. Is this Rube Goldberg circuit here what I want, or can I just use a 2x gain summing amp to sum CSYNC with the output of the blanking switch from C2?
