ARDUINO Burglar Alarm Using Infrared Emitter-Detector pair

Basic Idea:

In this tutorial i will show you , how to make a simple Inexpensive Intrusion Detection(Burglar alarm) using an Arduino Uno board . This project uses the Infrared Emitter-Detector pair to detect intrusion and triggers an alarm as soon as the object crosses the infrared field .
** To see a Similar Project Made with an LDR  click here
REQUIREMENTS :

1. Arduino uno R3
2. Breadboard
3. Connecting wires / Jumper cables
4. Infrared Emitter and Detector pair LED(not the sensor module) 
5. PCB mount BUZZER
6. 1kohm Resistor 
7. 10kohm Potentiometer

** the white LED is the Infrared emitter ,While the black is the Infrared Detector .

CIRCUIT DIAGRAM :

SOURCE CODE:



DISCUSSIONS:
First build the circuit according to the circuit diagram provided .
Now i will explain to you how the circuit works .

• The white Led you see in the pictures is an Infrared Emitter . You power it on like a normal LED . 
• Now if this is your first time with an IR Led , its very common that you'll mistake your LED to be spoiled as you wont find it glowing ,but that isn't the case really . 
• Infrared light is out of the visible spectrum range so even if it is glowing , you wont be able to see it with naked eyes .
•  To see if your emitter LED(White) is working properly : switch on your cell phone camera and see the LED through it , you will see that there is a purple Glow . 
• This ensures that your IR emitter (White ) is working perfectly and it is emitting light of a particular range of frequency . 
• Now lets come to the Black LED . The back LED is the IR detector. 
• The reason that it is made black is that Black color has the highest absorption ; so it Absorbs most of the infrared light Emitted by the Emitter . 
• Now what happens if an object stands in between the Emitter and the detector ?? . OBVIOUSLY the amount of infrared radiations intercepted by the detector will now be lesser due to the obstruction .
• This is the catch !! . When such a situation occurs , I trigger the alarm to denote Intrusion . 

Now that you've got your concept right , LETS FOCUS ON THE CODE . 

• In line 10 we begin the serial communication to see the values being intercepted on the serial monitor 
• for both the cases  i.e  
• case 1.) no obstruction in the path of the emitter and the detector . 
• case 2.)obstruction in the path of the emitter and the detector .
• for both these cases , we have to observe the values being reflected on the serial monitor , based on which we will decide for which value being exceeded we will be triggering the alarm .
• Note that for my experiment the threshold value was set to 1005 . This might not be the case for you. 
• Hence try to monitor the values that you are intercepting and choose your threshold accordingly .

Well , hope I have covered all the concepts in detail regarding this project . If you face problems or if you need further detailing on any sub-topic , then please do leave me a comment .

PROJECT VIDEO: