LDR Light Sensor Module, Photoresistor, Digital/Analog Output

This LDR (light-dependent resistor) module gives a straightforward way to detect ambient light levels, built around a photoresistor whose electrical resistance changes measurably with the amount of light falling on it - more light means lower resistance, less light means higher resistance, a simple and well-proven sensing principle that's been used in light-detection circuits for decades.

The module provides both digital (DO) and analog (AO) outputs from the same sensing element, giving flexibility in how a project uses the reading. Digital output gives a simple threshold-crossed high/low signal, driven through an onboard LM393 comparator chip, with a blue potentiometer letting the light-level trigger threshold be adjusted to match the specific lighting conditions and sensitivity a project needs. Analog output instead gives a continuous voltage proportional to light level, letting a microcontroller read and process the raw light intensity trend rather than just a binary threshold crossing.

Onboard indicator LEDs give immediate visual feedback: a red power LED confirms the module is receiving power, while a separate green LED lights up whenever the digital output triggers, letting a builder visually verify the sensor and threshold setting are working correctly even before anything is connected to read the output. The compact 3cm x 1.6cm PCB includes a mounting bolt hole for secure fastening inside an enclosure, and operating voltage spans the common 3.3 to 5V range.

Makers building an automatic nightlight, a light-triggered alarm or notification system, a simple photography light-meter project, or any application needing basic ambient light detection will find this LDR module a well-proven, inexpensive, and simple-to-wire starting point.