I’m designing a module(1) that’s going to have RCA Sync In (to a LM1881) and I’d like to have RCA Sync Thru also, but I’m not sure the best way to accomplish this. I had been planning on using the portion of the Cadet 1 schematic that does this. Video/sync in, terminated by 75R to ground, and it goes to a LM6172 buffer via a 499R (and to the LM1881 via a cap), and the buffer outputs the thru signal:
But recently I noticed that Syntonie’s VU001 handles Sync Thru a little differently… Input is directly tied to output, a jumper can terminate input to ground if you want, and input goes to a LM6172 buffer via a 499R and continues to the rest of the circuit:
So, I’m curious if @creatorlars or @syntonie (or anyone else who understand video electronics!) would care to comment on benefits/drawbacks to the different methods. One thing I like about the Cadet method is that users never have to deal with a termination jumper, since the input is always terminated. I don’t have anything that syncs via RCA, so I can’t test for any noticeable differences in behavior.
(1) I’ll be talking about my module more soon, but as a teaser, it’s a simple Arduino Nano-based module that’s being designed to be a multifunction cool-lowres-digital-shapes/text generator. Hopefully some people are interested in it, but even if they’re not, I won’t mind… I’m mostly designing it for myself since it’s something I really want.