Build a Motion Sensor-Controlled LED!

A motion sensor-controlled lamp is a simple and useful project that teaches you how to work with sensors and microcontrollers. It’s great for automatically turning on a light when someone enters a room, cupboard, or hallway.

Components

What you need:

Microcontroller (Arduino Uno or Nano)
PIR Motion Sensor (HC-SR501)
LEDs (as many as you’d like)
220Ω Resistor
Jumper Wires
Breadboard
Power Source (USB or battery)
3D printer (optional, for enclosure)
CAD Skills (optional, for designing the case)

Steps to follow when making your first motion-sensor lamp

Sketch the setup
Draw out the simple circuit:
- The PIR sensor detects motion
- The Arduino turns on the LED
- This helps plan where each component will be placed on the breadboard.
Connect the PIR sensor to the Arduino
- VCC → 5V
- GND → GND
- OUT → Digital Pin (e.g. D2)
- Place the sensor where it has a clear field of view. You can adjust its sensitivity and delay using the two onboard knobs.
Connect the LEDs to the Arduino

Sensor Controlled LED
- One end of the 220Ω resistor connects to Digital Pin (e.g. D3)
- The other end of the resistor connects to the positive leg of the LED
- The negative leg of the LED goes to GND
- Each LED has their own resistor and digital pin.
- The resistors limit the current to the LED and prevents them from burning out
Write the code
Use ChatGPT to generate Arduino code that:

- Reads the signal from the PIR sensor
- Turns the LED on when motion is detected
- Turns it off after a short delay

You can test the code and circuit using the Arduino IDE and a physical breadboard, or simulate it in TinkerCAD.

You can customise the code however you’d like.

Guidelines / Tips to making your Motion Sensor Lamp

Place your PIR sensor properly
- PIR sensors detect infrared radiation (body heat) best when the motion is across their field of view, not directly towards or away from them.
Adjust sensitivity and timing
- Use the onboard potentiometers to fine-tune how sensitive the sensor is and how long the output stays HIGH after detecting motion.
Use a diffuser or lampshade
- Add a piece of frosted plastic or paper over the LED to make it look more like a soft ambient light source.
Test with different lighting conditions
- Some PIR sensors are affected by strong ambient light or heat sources. Try testing in both bright and dim areas.

How to develop your project

Add a low-light condition
- Use an LDR (light-dependent resistor) so the LED only turns on when it’s both dark and motion is detected.
Add a second LED
- Use different LEDs for different purposes — one as a status light (e.g. motion detected), and one for illumination.
Turn it into a nightlight
- Combine with a small 3D printed case or lampshade to make a functional motion-activated nightlight for your room.
Power it with a battery
- Make the project portable using a 9V battery or power bank (if using a USB-based Arduino board).