The circuit is from a June 1995 Electronics Now. The relay is power-dependent and both R1 and R2 should have close resistances in operation.
Activating a relay from pulses (from a monostable, for example) can be useful in many types of...
This project uses an unusual integrated circuit that consists of a programmed timer. The circuit was...
I found this circuit in a Popular Electronics from 1992. The circuit shows how we can receive...