This circuit can be used as an answering password system in a store, office, or other location. The circuit is from Intersil using components of the time. The circuit is from the 80's.
This simple circuit, which appears elsewhere on this site, was found in a transistor manual from...
This transistorized astable for LEDs was found in the January 1992 issue of Radio Electronics...
This circuit works like a solid-state contactor. We find it in General Electric documentation from...