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.
The basis of this circuit is the 723, an old integrated circuit not easier to find these days. The...
This circuit was found in a May 1981 Radio Electronics magazine article. The circuit is offset...
The circuit presented was found in a Japanese magazine in 1973. The circuit uses transistors of...