The post explains a simple laptop anti-theft alarm circuit which can used with any concerned object such as a laptop which needs to be protected, when an intruder tries to approach the unit or makes an attempt to steal it the connected alarm is instantly raised. The idea was requested by one of the dedicated readers of this blog.

Technical Specifications


i have a problem and i hope you will solve this, last month some one stole my laptop in my hostel,

i am very angry about this lost i want to make ir transmitter and receiver circuit which operates the relay 12v iam very thankful to you i have also made the transmitter it works but receiver doesn't work i want to request you to make tr.and re very simple and easy work about 5 to 10 feet distance.

i have also spend money but all in vain help me sir very soon thank you

The Design


The laptop anti-theft alarm circuit could be possibly implemented by incorporating any of the following circuit concepts"

a tilt sensor circuit, a capacitive touch sensor circuit, an IR sensor circuit, a finger touch sensor circuit.

Using an IR proximity sensor circuit as shown below, is an effective way of tackling the theft issue, however the circuit could be relatively complex to build, adjust and apply.





The entire explanation for the above circuit may be found in this accurate proximity detector circuit article

A much simpler approach could be by employing a capacitive sensor switch circuit as shown below.

The supply will need to be operated from a 6V or a 12V battery.

The unit could be attached with the laptop, anybody coming close or trying to get hold of the object would instantly trigger the alarm.

The concept has been explained comprehensively in this capacitive touch sensor circuit article

Circuit Diagram


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