Motion Sensing Light Using Arduino & PIR Sensor

Hey guys welcome back to the techatronic. today we are going to make a very useful project. The product is motion sensing light bulb using arduino so in this project we are using a bulb which is turn on an off using motion sensing. So whenever a motion occurs the bulb will turn on.

Introduction

A motion sensing light using Arduino and PIR sensor is one of the most useful and beginner-friendly electronics projects you can build at home. Whether you want automatic lighting for staircases, bathrooms, corridors, garages, or outdoor pathways, this project provides a smart, energy-efficient solution.

Instead of keeping lights ON all the time, a PIR motion sensor detects human movement and automatically turns the light ON only when motion is detected. After a fixed delay, the light turns OFF again, saving electricity and improving convenience.

In this detailed guide, you will learn:

How a PIR sensor works
How to connect a PIR sensor with Arduino
Complete circuit explanation
Arduino code for motion sensing light
Real-world applications
Troubleshooting tips
Safety precautions

This Arduino PIR motion sensor light project is ideal for beginners, students, and DIY enthusiasts.

What Is a Motion Sensing Light using Arduino?

A motion sensing light is an automatic lighting system that turns ON when motion is detected and turns OFF when no movement is present. These lights are widely used in:

Home security systems
Automatic room lighting
Energy-saving lighting solutions
Smart homes

In this project, motion detection is done using a PIR (Passive Infrared) sensor, and the control logic is handled by an Arduino Uno.

Components Required

To build this Arduino motion sensor light, you will need the following components:

Hardware Components

Arduino Uno
PIR Motion Sensor (HC-SR501 or equivalent)
Relay Module (5V)
Bulb or LED (AC or DC load)
Breadboard
NPN Transistor (if not using relay module)
Resistor (1kΩ – 10kΩ)
External power supply (if required)
Jumper wires

Software Required

Arduino IDE
USB cable for Arduino programming

Understanding the PIR Motion Sensor

What Is a PIR Sensor?

A PIR (Passive Infrared) sensor detects infrared radiation emitted by warm objects like humans and animals. When a person moves in front of the sensor, the infrared pattern changes, and the sensor outputs a HIGH signal.

PIR Sensor Pins

Most PIR sensors have three pins:

VCC – Power supply (5V)
OUT – Signal output
GND – Ground

How PIR Sensor Works

No motion → Output LOW
Motion detected → Output HIGH

This HIGH signal is read by the Arduino, which then turns ON the light.

How Arduino Controls the Motion Sensing Light using Arduino

The Arduino Uno acts as the brain of the project. It continuously reads the output pin of the PIR sensor.

Working Logic:

PIR detects motion
PIR output goes HIGH
Arduino reads the signal
Arduino activates relay
Light turns ON
After delay → Light turns OFF

This logic makes the motion sensing light using Arduino fully automatic.

Circuit Diagram Explanation

Based on the attached circuit diagram, let’s break it down simply.

Arduino Connections

5V pin → Breadboard positive rail
GND pin → Breadboard ground rail

PIR Sensor Connections

VCC → 5V
GND → Ground
OUT → Arduino digital pin (example: D8)

Relay Module Connections

IN → Arduino digital pin (example: D7)
VCC → 5V
GND → Ground

Load (Bulb) Connections

Bulb connected through relay NO (Normally Open) terminal
External power supply used for the bulb

⚠️ Important Safety Note:
If you are using AC mains voltage, ensure proper insulation and safety precautions.

Arduino Code for Motion Sensing Light

Here is a simple and reliable Arduino code for the PIR motion sensor light project:

int pirPin = 8;     // PIR sensor output pin
int relayPin = 7;  // Relay control pin

void setup() {
  pinMode(pirPin, INPUT);
  pinMode(relayPin, OUTPUT);
  digitalWrite(relayPin, LOW);
  Serial.begin(9600);
}

void loop() {
  int motion = digitalRead(pirPin);

  if (motion == HIGH) {
    digitalWrite(relayPin, HIGH); // Turn ON light
    Serial.println("Motion detected - Light ON");
    delay(10000); // Light ON time (10 seconds)
  } else {
    digitalWrite(relayPin, LOW); // Turn OFF light
    Serial.println("No motion - Light OFF");
  }
}

How the Code Works

Reads PIR sensor output
If motion is detected → Relay turns ON
Light stays ON for 10 seconds
After delay → Light turns OFF

You can adjust the delay time as per your requirement.

Applications of Arduino PIR Motion Sensor Light

This motion sensing light project using Arduino has many real-world applications:

Home Automation

Automatic room lights
Bathroom and corridor lighting

Security Systems

Intruder detection
Automatic outdoor lights

Energy Saving

Lights only turn ON when needed
Reduces electricity bills

Smart DIY Projects

Smart stair lighting
Garage lighting
Garden lights

Advantages of Motion Sensing Lights

Saves electricity
Fully automatic operation
Easy to build and modify
Low cost
Improves safety and convenience

Common Problems and Troubleshooting

Light Always ON

PIR sensitivity too high
Incorrect wiring
Floating input pin

Light Not Turning ON

PIR sensor not powered
Wrong Arduino pin selected
Relay wiring issue

False Triggering

Place PIR away from heat sources
Adjust PIR sensitivity and delay

Tips for Better Performance

Use a relay module with opto-isolation
Adjust PIR potentiometers properly
Use stable power supply
Add delay logic in code
Test with DC bulb before AC load

Safety Precautions

⚠️ Always follow these safety rules:

Do not touch live AC wires
Use proper insulation
Keep Arduino isolated from high voltage
Test with low voltage first

Future Improvements

You can enhance this Arduino motion sensor light by adding:

LDR for day/night detection
ESP8266 or ESP32 for IoT control
Timer settings
Buzzer or alarm
Mobile app control

FAQs – Motion Sensing Light Using Arduino

Can I use LED instead of bulb?

Yes, you can use DC LEDs directly without relay.

What is the range of PIR sensor?

Typically 5–7 meters.

Can I power everything from Arduino?

Only for low-power loads. Use external power for bulbs.

Is this project beginner-friendly?

Absolutely! This is one of the best beginner Arduino projects.

Conclusion

Building a motion sensing light using Arduino and PIR sensor is a practical and rewarding DIY project. It helps you understand sensors, microcontrollers, automation, and energy-efficient design.

With simple components and basic Arduino programming, you can create a smart lighting system suitable for homes, offices, and security applications.

If you are learning Arduino or planning to explore home automation projects, this PIR motion sensor light is a perfect starting point.

Techatronic

Motion Sensing Light Using Arduino and PIR Sensor (Complete DIY Guide)

Introduction

What Is a Motion Sensing Light using Arduino?