NE 555 ic based wired security alarm diy electronic circuit

First published in my old blog at ziddique.wordpress.com in 2011

The security circuit posted here is a simple wire trap system, if the wire from “A” to “B” is broken, the buzzer that is connected to pin 3 of the ic will start “beeping” continuously.

Use a tiny copper wire as Trap wire,so the wire will easily break when someone try to enter to the area where this trap wire is placed.

Simple Wire Trap Alarm Circuit

The working of 555 wire trap circuit

An NE555 timer ic is used here as a “Free running oscillator, since the “pin 4” is connected to negative (GND) of the circuit, the buzzer will not work because the IC is disabled by the “Trap wire”, so if the trap wire is broken, the ic will be enabled and the buzzer will beep.

You may attach a loud siren to pin3 of the ic instead of buzzer so it will help you to know that your property is going to be robbed even if you are sleeping.

You can use a 9V battery for the easy use of this circuit

Components you need

R1 – 47K
R2 – 100K
R3 – 4.7k (4k7)
C1 – 16V/1000uf

IC – NE555
9V battery and its holder (if needed)
9V buzzer or siren (might need modification in the circuit if you want to use a high power siren)

need any help? just add a comment below!