An Arduino-based automation project that uses a Light Dependent Resistor (LDR)
to control an AC lighting circuit based on ambient light conditions.
The system automatically switches the load ON during low-light conditions
and OFF when sufficient natural light is available, improving energy efficiency.
This project demonstrates the practical application of sensor-based automation using an Arduino microcontroller. An LDR sensor continuously monitors ambient light intensity, and based on predefined threshold values, the Arduino triggers a relay module to control an AC lighting load.
The system supports both digital control and analog control modes, allowing flexible sensitivity adjustment depending on environmental conditions.
- Automatic ON/OFF control based on ambient light intensity
- Digital and analog control modes
- Energy-efficient lighting automation
- Simple and cost-effective design
- Suitable for outdoor and indoor lighting applications
The following diagram shows the interfacing of the LDR sensor module, relay module, and Arduino Uno used in this project.
- Arduino Uno
- LDR Sensor Module
- 5V Relay Module
- AC Bulb (Demo Load)
- Connecting Wires
- External Power Supply
- Platform: Arduino IDE
- Language: Arduino (C++)
- Microcontroller: ATmega328P
The LDR sensor detects changes in ambient light intensity and provides an analog or digital signal to the Arduino microcontroller. When the detected light level falls below a predefined threshold, the Arduino activates the relay module, turning the AC lighting load ON. When the light level exceeds the threshold, the relay is deactivated, turning the load OFF.
This automation ensures optimal lighting while minimizing unnecessary energy consumption.
The complete project report is available as a PDF:
- Automatic street lighting systems
- Home lighting automation
- Parking lot lighting control
- Energy-efficient outdoor illumination
- Integration with IoT platforms for remote monitoring
- Adaptive thresholding using environmental data
- Replacement of relay with solid-state switching
- Power consumption monitoring
This project is intended for academic and educational purposes.