This alarm circuit with NC sensors in series was taken from an article in Radio Electronics magazine from May 1971. The SCR can be any of the 106 series.
We found this circuit in the April 1975 Radio Electronics magazine. The circuit has a latch and...
We found this sophisticated home alarm in a 1994 documentation. The circuit supports sensors of...
This circuit was found in the 1991 Electronics Experimenter's Handbook. It activates a relay when...