LDR Sensor Module

The LDR Sensor Module is a compact and easy-to-use light detection module designed to sense changes in ambient brightness and trigger digital control signals in electronics, Arduino, robotics, and automation projects. Built around an LDR (Light Dependent Resistor) and an LM393 comparator, the module provides a simple way to detect whether surrounding light has crossed a user-defined threshold.

Its onboard potentiometer lets you adjust the light sensitivity according to your application, making it useful for both indoor and outdoor light-activated projects. The module operates from 3.3V to 5V DC, allowing convenient integration with many microcontrollers and development boards.

The digital output can be connected directly to a microcontroller input to create automatic responses such as switching lights, activating relays, triggering alarms, or detecting changes in environmental illumination. Onboard power and status LEDs provide quick visual feedback during testing and troubleshooting.

With its compact PCB, M3 mounting hole, adjustable sensitivity, and simple three-pin interface, this LDR light sensor module is a practical choice for students, makers, electronics enthusiasts, and engineers building light-sensitive circuits, IoT prototypes, and automation systems.

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Features:

• Adjustable sensitivity via blue digital potentiometer adjustment
• Digital output range: 0V to 5V
• Adjustable trigger level from preset
• LEDs indicating output and power (Power indicator in red and digital switch output indicator in green)
• Uses LM393 comparator chip for stability
• Easy to install with an M3 mounting hole for attachment
• Suitable for detecting ambient brightness and light intensity
• Digital output for easy integration with microcontrollers
• Comes with a power LED and status LED as indicators

Applications:

• Control lights with LDR sensors.
• Adjust streetlights for energy savings.
• Trigger alarms in security.
• Monitor sunlight for plants.
• Optimize camera settings.

Pinout:

How to Use:

• A photosensitive resistor module most sensitive to environmental light intensity is generally used to detect the ambient brightness and light intensity.
• Module light conditions or light intensity reach the set threshold, DO port output is high when the external ambient light intensity exceeds a set threshold, the module D0 output is low;
• Digital output D0 is directly connected to the MCU, and detects high or low TTL, thereby detecting ambient light intensity changes;
• Digital output module DO can directly drive the relay module, which can be composed of a photoelectric switch;

Read our blog explaining how LDR works.