Sync generation from non lzx equipment?

I saw the schedule update about chromagnon the other day and realized it’s gonna be another ~4 months until I can use the modules I’ve built and the few Orion modules I’ve bought over the last 10 months or so… And I’ve got a 2 part question.

I managed to scoop up one of the cadet2 boards that were on sale a couple weeks back and I was wondering if I can sync them with the sync signal my Sony SVO-5800 VCR generates? It outputs c-sync via a bnc on the back, and has trimable tbc controls on the front.

And question 2: if the csync output from here is able to sync the Orions would it sync C2? I see on the C2 schematic that it needs csync and blanking… is there any relatively easy way to do this? The circuit on C1 needs the ATMega to generate blanking :confused: I found this TDA1180p that says it can generate blanking. Is there a way to buffer csync, mult the signal, send one csync to the blank generating circuit in the 1180p data sheet then send the blanking and the other csync to C2? And if there is can somebody help me with this? I’m a super beginner with all this…

1 Like

You’re on the right track. You need to derive blanking from the csync since C2 needs blanking (because the AD724 encoder IC needs it). I’m not entirely sure how LZX generates/derives blanking in the atmega in C1, but another way to do it is by using a couple one-shots tuned to the right timing, ala how Rob Schafer does it here: Lesson 6 - BLANKING (finally) - YouTube

His video electronics work a little differently from LZX stuff, since he’s using single-supply opamps set up to use 0V as -V, 5V as +V, and 2.5V as virtual ground, but the timing concepts are fairly transferable. In some ways, his method is not as clean as LZX’s atmega approach, since it involves adjusting some trimpots until the timing is right, which is best done with a scope that can handle video rates, but it is one way to do it.

Alternatively, if you can put together your own C1 from the schematics, LZX might be up for sharing the hex file so you can flash the atmega. I’m pretty sure they don’t share the code itself, but you don’t need the code to get a C1 to work, just the compiled hex file.

(BTW, all of Rob’s lessons are pretty interesting and worth watching even considering how they differ from LZX circuits.)

1 Like

I should add: I haven’t actually tried to adapt Rob’s circuits to LZX compatible stuff myself, or duplicate this blanking deriver, so I can’t just share some schematics with you, unfortunately.

The ELF for Cadet I is here. I’ve used it to flash my C1 before with Atmel Studio.

1 Like

Oh, these are super interesting! The way he operates in a unipolar 0-5v environment forces him to be very creative at times.


I am 75% done putting together a module to solve this issue of composite sync to lzx sync.

The board is a summary of a few different approaches and is inspired by c1, the lMH1980/81, nootropics’ video explorer, and a few other bits of idea surrounding one shots.

The sloppy idea is that it’s a bunch of tools that could all be used to get all the pieces you need to Make at least something resembling the data lines in a 14p lzx sync signal - in different ways. Probably overkill (dumb?) at this point but I’d personally rather do this than a jenky breadboard since a bunch of the components are SMT.

I think where I left it was dealing with blanking so I’m happy to look at that Ic you’ve suggested. Especially if it solves that part of the equation in one big chunk…

more Than happy to big-brain this together; it’s kinda nice to know someone else is hitting their head on this (not just me).

I should note I started this madness by doing a respin of c1 but, issue was finding the VCXO … does anyone have / a source for that or one
With similar voltage and rate?