Wire loop theft alarm

Posted on Oct 31, 2012

This circuit utilising a 555 timer IC can be used as an alarm system to prevent the theft of your luggage, burglars breaking into your house etc. The alarms goes ON when a thin wire, usually as thin as a hair is broken. The circuit is straightforward. It uses a 555 IC wired as an astable multivibrator to produce a tone of frequency of about 1kHz which gives out a shrill noise to scare away the burglar. The wire used to set off the alarm can be made of a thin copper wire like SWG 36 or higher. You can even use single strands of copper form a power cable.

Wire loop theft alarm
Click here to download the full size of the above Circuit.

The circuit operates on a wide range of voltages from 5V to 15V. The speaker and the circuit could be housed inside a tin can with holes drilled on the speaker side for the sound to come out.

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