Intruder alarm detector system - uses metallic sheets separated by insulating sheet fixed to doors or walls and piercing of sheets triggers alarm

摘要

The break in detector is formed from two metallic sheets (1, 2) which sepd. from each other by an insulating sheet (3). The metallic and insulating sheets (1-3) are fixed on the rear of door panels (4). The two metallic sheets (1, 2) are connected by wires (11, 22) to an alarm circuit. Any hole made in the door (4) by a metal object which pierces the sheets electrically interconnects the metallic sheets and triggers the alarm. The sheets are fixed to the door panels by wood screws and insulating washers and packers.