This alarm circuit was found in April 1975 Radio Electronics magazine. The circuit uses a 12 V power supply and relay but can be modified to work with other voltages.
This circuit is from a 1998 Electronics Now and can be easily assembled since it uses a common...
We find this circuit in an American 80's documentation. No further information about the...
With this circuit, an external circuit can be controlled by turning it on or off and reversing it (if...