Build an Auto Light Energy Saver with Arduino Uno, LDR, and PIR Motion Sensor

Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.

With this kit, you’ll build a light controller that never wastes electricity — it only activates when someone enters a dark room and stays off during daylight motion. By combining a passive infrared (PIR) sensor with a light-dependent resistor (LDR), you create a system that mirrors real-world home automation, like in corridors, bathrooms, or storerooms where lights are often left on for hours.

What You'll Build

A fully functional automatic lighting unit that detects human presence and measures ambient brightness to decide when to power a bulb or appliance through the relay. The system displays status on a 16x2 LCD — ‘Motion: YES/NO’ and ‘Light: LOW/HIGH’ — giving you clear, real-time feedback as it saves energy.

What You'll Learn

• How to interface an HC-SR501 PIR module with Arduino to detect motion
• Using an LDR with a voltage divider to measure ambient light levels digitally
• Driving a 5V relay to safely switch AC loads, with flyback diode protection
• Displaying real-time sensor data on an I2C LCD and building a clean breadboard circuit

Kit Contents

Why Buy This Kit Instead of Sourcing Parts Separately

Who This Kit Is For

This kit is ideal for CBSE Class 11 and 12 students tackling their physics investigatory projects or computer science practicals. B.Tech ECE/EEE students will find it a ready-made mini project for first-year labs or Smart India Hackathon prep. ATL Tinkering Labs and hobby clubs at IIT, NIT, VIT, or BITS can use it to prototype energy‑conscious automation in a single afternoon.

Built and Backed by Compoden

Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.