I'm still having trouble wrapping my head around the single relay version, unfortunately.
The zero relay version I definitely won't be trying. If this were 5v and mAmps, maybe I'd be game - but we're talking line voltage here.
If anything, at least the thread is out there now. None of my previous searches turned up anything in the ballpark.
Stop worrying about grain, resolution, sharpness, and everything else that doesn't have a damn thing to do with substance.
It's simple. When neither enlarger is on, the outputs for both safelights are energised. This turns on the relay whose contacts then connect the safelight to the output of the other timer.
Originally Posted by clayne
If timer 1 switches the safelight off, the relay disconnects the safelight from timer 2.
If timer 2 switches the safelight off, it doesn't matter where the relay is as there is no power being supplied to power the safelight.