PIR Based Theft Alert System Using Arduino Uno (Beginner Project)

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 PIR based theft alert system

Working of PIR Sensor

 Introduction

In this project, we will build a PIR-based Theft Detection System using an Arduino Uno.

This system detects unauthorized human movement and activates:

  •  A buzzer (audio alert)

  •  An LED (visual alert)

It is a simple and practical security system project for school exhibitions and beginners.

You can simulate this project in Tinkercad.

 Working of PIR Sensor

A PIR (Passive Infrared) Sensor detects infrared radiation emitted by warm objects like humans and animals.

How It Works:

  • The PIR sensor contains two IR-sensitive slots.

  • When no motion is present, both slots detect equal IR radiation.

  • When a human passes by:

    • One slot detects more IR than the other.

    • This creates a differential signal.

    • The sensor outputs a HIGH pulse.

  • When motion stops, the signal returns LOW.

The Arduino reads this HIGH signal and triggers an alarm.

 Components Required

  • Arduino UNO

  • PIR Motion Sensor

  • Buzzer

  • LED

  • 220Ω Resistor

  • Breadboard

  • Jumper wires

Circuit Connections

PIR Sensor:

  • VCC → 5V

  • GND → GND

  • OUT → Digital Pin 2

LED:

  • Anode (+) → Digital Pin 8 (through 220Ω resistor)

  • Cathode (–) → GND

Buzzer:

  • Positive → Digital Pin 9

  • Negative → GND

Arduino Code

int pirPin = 2;
int ledPin = 8;
int buzzerPin = 9;

void setup() {
  pinMode(pirPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
}

void loop() {

  int motion = digitalRead(pirPin);

  if(motion == HIGH){
    digitalWrite(ledPin, HIGH);
    digitalWrite(buzzerPin, HIGH);
  }
  else{
    digitalWrite(ledPin, LOW);
    digitalWrite(buzzerPin, LOW);
  }

}

 How the System Works

  1. PIR sensor continuously monitors infrared radiation.

  2. When motion is detected:

    • PIR sends HIGH signal to Arduino.

    • Arduino turns ON LED.

    • Arduino activates buzzer.

  3. When no motion is detected:

    • LED and buzzer remain OFF.

Learning Outcomes

Students will learn:

  • Motion detection using PIR sensor

  • Digital input and output control

  • Basic security system design

  • Real-world embedded system applications

 Real-World Applications

  • Home security system

  • Office intrusion detection

  • Restricted area monitoring

  • Smart IoT security projects

  • Automatic light activation systems

 Troubleshooting Tips

  • Wait 30–60 seconds after powering PIR (calibration time).

  • Adjust sensitivity using onboard potentiometer.

  • Ensure correct wiring of OUT pin.

Circuit diagram:


This project simulates a theft detection and alert system using a PIR motion sensor connected to an Arduino UNO. The system detects unauthorized movement using the PIR sensor. When motion is detected (such as a person entering a restricted area), the Arduino triggers a buzzer and LED to alert the user, simulating a real-world theft alert scenario.The PIR sensor constantly monitors for infrared radiation (body heat).When it detects motion (a person moving), it sends a HIGH signal to the Arduino.The Arduino then turns ON the buzzer for an audible alarm and turns ON the LED for a visual alert.If no motion is detected, both the buzzer and LED remain OFF.


Code:



Try this in Tinker cad :



PIR based theft alert system using tinker cad

BEGINNER PROJECTS (Foundation Skills)

  1. Ultrasonic Distance Measurement
  2. Traffic Light Simulation with 7-Segment Display
  3. 7-Segment Display Counter
  4. Kids Piano Circuit (8-Key Version)
  5. 16×2 LCD Display with Text Output
  6. LCD I2C to Arduino UNO
  7. Temperature Measurement using Arduino UNO
  8. LDR Controlled Street Light

INTERMEDIATE PROJECTS (Build Your Skills)

  1. Servo Motor Control Using Potentiometer
  2. DC Motor Speed Control
  3. Temperature Controlled Fan
  4. PIR Based Theft Alert System
  5. LPG Gas Leakage Detection System
  6. Automatic Door Locking System
  7. Soil Moisture Based Automatic Watering System
  8. Simple Digital Clock using Arduino UNO
  9. Automatic Voting Machine (EVM)
  10. Joystick Control using Arduino Uno
  11. RGB Lamp Control using Arduino Uno

    ADVANCED PROJECTS (Master Level)

    1. Home Automation Using Arduino UNO
    2. Bluetooth RC Car using Arduino Uno
    3. Obstacle Avoiding Robot
    4. Line Follower Robot
    5. Radar System Using Arduino UNO
    6. Automatic Parking System
    7. Bi-Directional People Counter using Arduino Uno 
    8. Automatic Plant Watering System
    9. NeoPixel LED Ring Control using Arduino Uno
    10. Smart Gloves for Bedridden People

      ROBOTICS & MOTION PROJECTS

      1. RC Car Using L293D Motor Driver
      2. Robot Arm and Leg Control Using Servo
      3. Smart Irrigation System using Arduino Uno

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