@▷ wire loop alarm | Diagram for Schematic

wire loop alarm

This circuit is a simple wire loop alarm that can be used in doorways, hallways, or any other place the tripwire will be broken by intruders. The circuit has a built in siren, but it can be replaced by a relay to drive an external siren, commercial alarm, etc.

alarm1 wire loop alarm
alarm1 wire loop alarm

Notes:

1. Email Alex Meaden with questions, comments, etc.

2. The loop can be any type of hookup wire, with a maximum resistance of about 90K. Using very thin wire (40AWG, for example) will make a very sensitive trip wire, but will shorten the distance it can be strung due to the high resistance.

3. The siren can be replaced with a relay to drive external loads.

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