We found this circuit in a 70s RCA manual. The circuit uses an LDR by directly driving a sensitive relay. Resistor R1 is 5.6 ohms and R2 is 25k. The pot is 10k of wire.
The circuit below was suggested by the Motorola Linear Databook of 1990. The component used is...
The circuit of the figure consists of a motor timer that can delay drives for up to 15 minutes....
We found this circuit in a 1960 Sylvania transistor manual. The relay can be 12 V and C1...