This circuit is from a March 1978 Radio Electronics magazine article that showed how to build it. The circuit is TTL based and is powered. The components used can still be found.
This immobilizer circuit for the car was found in the Radio Electronics magazine of December 1976....
This circuit allows the activation of a remote telephone bell made with a common piezoelectric capsule. The...
This circuit can act as a receiver for the transmitter of the previous circuit. We found it in...