LDR Light Sensor Module

This LDR Light Sensor Module is a ready-to-use photoresistor based light detection board designed for fast prototyping of light-sensitive circuits. The on-board LDR changes resistance according to the ambient light falling on it. In brighter conditions its resistance reduces, and in darker conditions its resistance increases. The module uses an LM393 comparator circuit to convert this changing light level into a clean digital signal, making it easy to interface directly with microcontroller GPIO pins. The module operates on a 3.3V to 5V DC supply, so it is suitable for popular development boards such as Arduino Uno, Arduino Nano, ESP8266, ESP32, Raspberry Pi Pico, NodeMCU and other TTL-level controller boards. A small preset potentiometer is provided to adjust the switching threshold, allowing you to decide at what brightness level the digital output should change state. Many LDR sensor module versions also provide an analog output pin, which can be connected to an ADC input when you need proportional light intensity measurement instead of only ON/OFF detection. For visibility during testing, the board commonly includes a power LED and a status LED for the comparator output. This makes the sensor especially useful for classroom demonstrations, robotics labs and quick bench testing without needing extra indicators. It is widely used in automatic night lamps, smart street-light models, solar tracking experiments, light-following robots, burglar alarm triggers, display brightness control prototypes and general ambient light monitoring systems. Typical pin notes: VCC connects to 3.3V or 5V, GND to ground, DO to a digital input pin, and AO, where provided, to an analog input pin. Package contents: 1 x LDR Light Sensor Module with on-board LDR, LM393 comparator circuit, threshold potentiometer and indicator LEDs.