Wire loop alarm

Posted on Feb 6, 2014

Here is the circuit diagram of a very simple wire loop alarm based on a N-channel enhancement FET 2N700, a buzzer and few passive components. In normal condition the gate of 2N700 (Q1) is connected to the ground through a 100K resistor (R2) and the wire loop. When the wire loop is broken, Q1 will be biased to ON state and the buzzer is activated. T

Click here to download the full size of the above Circuit.

he circuit consumes very less standyby current and so the battery will last for a very long period of time.

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