In this article, we list different burglar alarm circuit and projects we have designed and published in CircuitsToday. A burglar alarm is basically an intruder alert system used to prevent theft/robbery and protect one’s premises. Burglar alarms or alert systems can be designed in different ways; from very simple sound alarm system to the advanced and feature rich system which will send SMS alerts, activate sound alarm, turn ON lights, turn ON CCTV cameras, close the main gate etc. The cost of building burglar alarm will go up with more features and new technologies incorporated into the system.

Let’s skim through different burglar alarm circuits, beginning from simple ones to advanced.

 Burglar Alarm Circuit using Arduino and PIR Sensor with GSM Module for SMS Alert

Burglar Alarm or Theft Alarm or Intruder Alarm using Arduino

In this project, we have designed 2 burglar alarm circuits using arduino and pir sensor. The first one is a simple burglar alarm circuit using pir sensor, arduino, a buzzer and a push button switch. The PIR sensor is used to monitor a particular location/field for any movement/motion. PIR sensor is basically a motion detector which is used as motion sensor in different real world applications. When a movement is detected inside the range of PIR sensor, arduino will activate the buzzer to produce a sound alarm. This activated sound alarm will continue until the “reset” push button switch is pressed by someone.

GSM Based Burglar Alarm Circuit using Arduino
Gsm based Burglar Alarm using Arduino and PIR Sensor

The second burglar alarm circuit using arduino is a little advanced one which uses GSM module to send SMS alerts to mobile numbers stored inside the arduino program. A SIM900 based GSM module is interfaced with the first circuit to incorporate the SMS facility.

Burglar Alarm using 8051 and PIR Sensor with SMS Alert – We have designed a burglar alarm using 8051 recently. We are yet to publish this.

Simple Burglar Alarm Circuit without Microcontroller

Next project is Burglar alarm without microcontroller! All the above burglar alarm projects we listed above made use of micro controllers like 8051, AVR, Arduino etc. We don’t need sophisticated micro controllers like 8051 to build a very simple burglar alarm circuit with minimal features. So let’s build a burglar alarm using transistor and scr as main components.

This simple burglar alarm circuit is designed using transistor BC107 and SCR TYN612. With minimal components used to design the system, this project is a cheap/low cost burglar alarm circuit.


Here is a simple but effective burglar alarm circuit that can be fixed on windows to detect break through. The circuit uses a fine wire element fixed as a network through the window  glass  for sensing the break through. Normally the base of Q1 is held to ground potential by the wire element.So Q1 will be off and SCR H1 will not be conducting,and horn will be off.When the wire element breaks,base of Q1 will be raised to positive potential, Q1 will be on and so SCR H1 (TYN 612) will be ON making the horn to blow and this condition will be latched by the SCR. The circuit remains ON until the normal condition is restored or the power supply is switched OFF.

Burglar Alarm Circuit Diagram with Parts List .
Burglar Alarm Circuit Schematic
Burglar Alarm Circuit Diagram
  • To make the window foil make a loop of very fine wire through the window glass ( two or three lines running in both direction is enough).See figure.Connect the two  free ends of the wires to point A & B as shown in circuit diagram.
  • To setup the circuit , make S1 open and adjust R2 to get a 1V between base of Q1 and ground.(0.7 V is enough to ON Q1).Now transistor will be ON and horn will be blowing.
  • Now ,close S1 and reset the power supply .The transistor Q1 will be  off and horn will not be blowing. The circuit is ready.
Making the window foil:
Window Foil Burglar Anti Theft Alarm
We have more Safety Circuits that you may be interested in; Take a look:

1. Metal Detector

2. Intruder Alarm

3. Shock Alarm Circuit

4. Night Security Light

5. Infra Red Barrier




  1. John Lery

    what scr could replace tyn612?the nearest one and base on your design?