Found in the September 1982 issue of Radio Electronics magazine, this circuit triggers a relay intermittently. Triggering is done by a reed switch, but other types of sensors can be used.
This voltage regulator step can be used for a variable source from 0 to 30 V with a maximum output...
This circuit was found in Popular Electronics from February 1967. Transistors are from the period....
In this oscillator circuit using 3 TTL inverters we have all the conditions for the frequency...