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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.
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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