Thanks for feedback SW.
you're going to have potentially long control cables?
Yeah I struggled with this decision but perhaps concerns are unfounded. Figured a bundle of shielded i/o wires are better than having a 'digital' pcb in each bucket (right under unbalanced fader lines) chunking away 24/7. I agree it would be much simpler to put extenders near the i/o endpoints. Looking for a slimline case to shield pcb's, but finishing is becoming more important than anything at this point. :/
Went so far as to order some I2C balanced extenders to test, but they haven't arrived yet.
Or, if you do it the way you have it layed out, what is the ground plane situation?
5v and Gnd planes included, quite objectively to drain those transistors and pull up button sensing i/o
Cut them out for sake of picture clarity-- oops
might be desirable to have a decent ground plane below (or above) those lines to the transistors with a really good ground wire to DGND running right next to (or loosely twisted around) the relay supply wire.
Yessr. Pulldown/debouncing circuits for relays are onboard each channel card that supplies 12v, and sinks most of it. I believe as long as m/c pcb's are tied to console dcom, max draw is 0.6mA @ ~3v per relay cv pin.
I should have put a dotted line around that relay buffer circuit on the previous page, they are already installed in each channel/group cards. The logic pcb only sinks cv, not the whole relay loop.
There are better ways to have implemented this whole thing, that's for sure. Live and learn.