This circuit was found in the December 1976 issue of Radio Electronics magazine. The circuit includes a powerful pulsating siren. It is activated by courtesy light switches and other sensors.
This circuit for photography uses was found in the Electronics Experimenter Handbook Special...
It is like to the previous circuit with a lock that keeps the LED on at the end of the timer. The...
This circuit, with two operationals, was obtained from an old American publication. Operational...