How to use a signal from mains to control a DC relay?


Joined Dec 31, 2017
requiring a much larger cap for the same holdup time.
Not really. I tested the circuit on 120vac (which would be worst case for the TS) using a 4.7uf cap with 47K resistors and a LED to simulate the opto.
The DC across the the LED had very little ripple, well below affecting the relay circuit.

Thread Starter


Joined Dec 15, 2009
So what about putting in both capacitors, one 4.7uF after the bridge, and one 2.2uF after the opto? Would that be advantageous?