The voltages shown were in the original design. From the original designer of the circuit: the relay's coil voltage rating is 1/2 the supply voltage. Each of the two resistors are equal to the coil's resistance. I've used 5VDC relays with a 12VDC supply and it worked fine. The value of the cap was just selected by experiment.
The voltages shown were in the original design. From the original designer of the circuit: the relay's coil voltage rating is 1/2 the supply voltage. Each of the two resistors are equal to the coil's resistance. I've used 5VDC relays with a 12VDC supply and it worked fine. The value of the cap was just selected by experiment.