Burglar Alarm Circuit

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In this tutorial, we are going to design a burglar alarm circuit. This circuit detects an unauthorized entry of any person into the houses or in any particular area. It is a simple and cost-effective solution for the security system. The project uses a PIR motion sensor instead of a Transmitter and a receiver.

The PIR motion sensor saves power consumption. PIR sensor stands for the “Passive Infrared sensor”. The PIR sensor has many useful features like changing the distance ranges, setting the alarm durations, etc. The burglar alarm project consists of a PIR sensor, a UM3561 IC, and a speaker which produces a sound after the detection of any movement.

Hardware Components

The following components are required to make Burglar Alarm Circuit

S. No	Components	Value	Qty
1	PIR Motion Sensor	–	1
2	IC	UM3561	1
3	Resistors	220K,10K	1, 1
4	NPN Transistor	BC547	1
5	Speaker	8ohm	1
6	Battery	9v	11
7	Breadboard	–

UM3561 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of UM3561

Working Explanation

The underlying principle of the burglar alarm project is to provide security. The project uses a PIR sensor with the IC. This combination produces an effective siren at the output. The UM3561 IC generates four different types of sound which are a police siren, a fire brigade siren, a machine-gun sound, and an ambulance siren. As the PIR sensor observes any kind of motion of any person, its output pin becomes high.

This output pin activates the IC which produces a siren with the speaker. The IC needs a transistor to amplify the current which drives the speaker. The speaker rings continuously by the siren of the IC. Its time duration is set by the PIR sensor’s Time delay control regulator. Some PIR sensor works on the AC voltage so a relay controls them.

Application

To protect the valuable things in the museum burglar alarm circuit plays a vital role.
It is a part of an automatic doorbell that detects any kind of motion and rings the bell.
The defense applications use a burglar alarm circuit to detect humans in war fields.