Based on Radio Shack 276-137, this circuit was found in the December 1995 issue of Electronics Now magazine. The circuit drives an LED but could use a relay instead.
This circuit is from a Radio Electronics magazine from July 1984. The transistor determines the...
This circuit was found at Electronics Now. It can be used as a shield detector for dial signals in an...
This circuit was obtained from an English circuit manual. Components are common and LEDs can be 3...