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 commercial circuit is from a Japanese magazine from 1967. It uses germanium transistors, and...
This circuit can be used to drive relays, solenoids, motors and other loads according the...
This circuit is based on the small keychain that responded to the sound of a whistle and were...