We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as sensors and drives relays. The relays must have voltages according to the power supply.
This filter that can use any operational was found in a French documentation from 1982. The power...
In the figure we present an extremely simple circuit of a voltage source regulated by a zener...
The maximum current of this power supply is 2 A and the output voltage can be set between 6 and 24 V. The...