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 amplifier is from Motorola's 1990 Linear Databook. The circuit can be used with operating...
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...
This inductively coupled oscillator was found in an American documentation from the 90's. The...