How to make a Burglar Alarm | DIY Burglar Alarm Tutorial

Hey guys, welcome back, In the previous post, I told you how an IR sensor works and how to make a line follower using an IR sensor. In this post, i will show you how you can make a Simple DIY Burglar Alarm using an IR sensor and a Buzzer without using any micro controller or complicated coding. 

DIY Burglar Alarm Components Needed

To set this up, All you need is

  • IR sensor
  • Breadboard
  • Buzzer
  • Some connecting Wires
  • 5 Volt Power Adapter

IR Sensor Burglar Alarm Video Tutorial

Burglar Alarm Video Tutorial

DIY Burglar Alarm Tutorial

About IR Sensor

If you are a beginner and new to Electronics and Robotics, you might have heard the name of this sensor multiple times – The IR Sensor. 

IR sensor mainly consists of an IR transmitter (IR LED) and an IR receiver (Usually a photodiode).

IR Sensor Burglar Alarm
IR Sensor

Most IR Sensor will be having 3 pins. The VCC (5V), GND (0V) and Vout (Output Voltage).

VCC will power up the sensor circuit. The Vout pin will give us an output voltage when the IR light is reflected back to the photodiode.

IR LED always emits IR rays to the direction it is pointing to. Now let us bring it closer to a surface. When the IR rays hit a surface, some rays will be reflected back depending upon the color of the surface.

Means, the brighter the color is, the more IR will be reflected back. Darker the color, more IR will be absorbed by the surface and lesser IR rays will be reflected back.

IR Sensor Working DIY Burglar Alarm
IR Sensor Working

These reflected rays are received by the Photodiode and depending upon the intensity of the received IR rays, the resistance of the photodiode varies which will, in turn, varies the output voltage.

Thus it is possible to sense the brightness of the surface by looking into the reflected IR rays.

DIY Burglar Alarm

So Now you know how an IR sensor works. We will start building our Burglar alarm.

This project is very simple. You wont need more than 1 minute to set this up. This is how we set up the entire circuit.

Here I will be bending the legs of the LED and photodiode so that they are facing each other. I will show you why I am doing this in a minute.

Connections – Burglar Alarm Circuit

The 5 V supply is connected to the IR sensor and the IR sensor Output is connected to the Buzzer.

IR Sensor
Vcc – 5V
Gnd – Gnd
Vout – +ve of Buzzer

+ve – Vout of IR Sensor
-ve – Gnd

You can use a breadboard to connect all of them together.

Fixing it on the Door

I have cleaned all the connection using a zip tie and this is what it looks like.

IR Sensor Burglar Alarm Neat

Now we can fix this on the door frame and power it up.

Now we need something to block the IR rays from LED from reaching the photodiode. For that you can use a black cardboard or a tape.

IR Sensor Burglar Alarm
IR Sensor Burglar Alarm

We can fix this on the door in such a way that when the door is closed, it will be placed in between the photodiode and the IR LED.

Burglar Alarm Working Explained

When the door is closed, the photiode will be facing the black surface and no IR rays will be reaching the photodiode and hence the output of the ir sensor will be Zero. 

When the door is opened, the photodiode will be facing the IR LED and the IR rays will be directly hitting the photodiode. This will cause the output voltage to go high and the buzzer connected to the output of IR sensor will start to beep.

New to Robotics?

We have a beginners guide on “Getting Started with Robotics” which will give you a kick start in this field. Check out our free video tutorial below for a brief introduction.

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