I'm just trying that doorbell mod where you turn a doorbell into a on/off remote and got a doorbell which takes 3 x 1.5 volt batteries and a 5 volt relay.
Problem is, when I opened it up, there is a wire going to part of the circuit board after the second battery (3volts).
What resister would I need to drop the current enough to power the 3volt side of the board.
I don't know what current is being pulled