Turn on an AC lamp using Arduino, 5V relay and motion sensor

This is a simple motion sensor project using Arduino. A 220V AC lamp is connected to a 5V relay and the relay is activated once the motion sensor senses motion and sends a signal to the Arduino.

List of materials

  • Arduino Uno ( Rev 3 )
  • Sensor ( PIR )  HC-SR501
  • Keyes SRD-05VDC-SL-C Relay Module or any 5V relay module
  • Socket
  • Bulb ( Incandescent lamp )
  • Suitable wires and jumpers ( thicker wires for a lamp connection, such as 1.5mm FiOS 2 ).
  • A breadboard or a protoboard to solder.

If you have never used a relay, you are recommended to read this article: How to use a relay

The code

const int negativeRELE = 10; 
const int pinPIR = 4; 

void setup () { 
  pinMode (pinRELE, OUT); 
  pinMode (pinPIR, INPUT); 

void loop () { 
  int valued = digitalRead (pinPIR); 
  if (value == HIGH) { 
    digitalWrite (pinRELE, HIGH); 
    delay (5000); 
    digitalWrite (pinRELE, DOWN); 

Running the Circuit

The project shown below has been added with an LDR/photoresistor. This gives the project an additional feature of responding to darkness and light. To test the circuit, simply move the front of the sensor to be triggered.

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