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.
Found in 1968 Mullard documentation, this circuit uses period components. The transistors are...
In the figure we have a modified multiplier circuit that can operate with the sextuplicator with...
This circuit converts signals from the 350 to 500 kHz band to the 4.36 to 4.5 MHz band, enabling...