This simple circuit, found in American documentation, uses only one relay that locks when any of the sensors is activated. To reset, simply turn off the power for a moment.
This circuit was found in the March 1982 Radio Electronics magazine. The component is a special...
This 1969 Electronics World power supply has 5 V to power digital circuits and a 170 V output for...
Found in Radio Electronics from the 90s, this circuit uses a thermistor as a sensor that can have...