LM393 4-Pin LDR Light Sensor Module Photosensitive Digital Switch 3.3V-5V for Arduino & ESP32

Specifications:

• Operating Voltage: 3.3V – 5V DC
• Output Signal Type: Dual (Digital Switching Output DO + Analog Output AO)
• Comparator IC: Onboard LM393 High-Precision Differential Comparator
• Light Sensing Element: Photoresistor (LDR)
• Output Current Drive: >15mA
• Sensitivity Adjustment: Onboard multi-turn potentiometer for digital threshold tuning
• Indicator LEDs: Power LED + Digital Output Status LED
• Weight: 0.010 kg [Estimated]
• Operating Temperature: -20°C to +70°C
• Pin Count: 4 Pins (VCC, GND, DO, AO)
• Compatible Platforms: Arduino, ESP32, ESP8266, Raspberry Pi (via ADC or DO), STM32

Unlock New Capabilities

• Past Projects (Prerequisites)
  If you've already experimented with basic LED blink projects on an Arduino Uno or controlled simple digital switches, you already understand GPIO input and output logic— which means you're completely ready to integrate automated environmental light sensing into your setups.
• Feature Upgrade (What This Unlocks)
  This LM393 LDR Light Sensor Module unlocks automated night-light activation, smart solar tracker adjustments, security intrusion detection via beam-break sensing, and ambient-light-compensated display dimming. These are dynamic, environment-aware automation projects you simply cannot implement using fixed timing loops alone.
• Effort Level & Minimum Hardware
• Effort Level: Beginner

Minimum hardware to get started:

• Arduino Uno, ESP32, or STM32 development board: required to process the module's digital switching state or analog light intensity voltage.
• 3.3V or 5V DC Power Source: required to power the onboard LM393 comparator circuitry; using voltages outside this range can damage the sensor or cause signal drift.
• 3× or 4× Jumper Wires (Female-to-Male): required to connect power, ground, and output signal pins to your microcontroller board.
• Breadboard (Optional): recommended for quick, solderless prototyping during initial bench testing.

Included in the Box:

• 1× LM393 4-Pin LDR Light Sensor Module

Frequently Asked Questions

• Is the LM393 LDR Light Sensor Module compatible with Arduino Uno?
  Yes, it is fully compatible with Arduino Uno using either standard digital GPIO pins or analog input pins.
• Can I use this light sensor module with an ESP32 or ESP8266 board?
  Yes, the module works seamlessly with ESP32 and ESP8266 development boards when powered at 3.3V.
• Does this module work with Raspberry Pi?
  Yes, the digital output (DO) pin can be connected directly to Raspberry Pi GPIO pins, while the analog output (AO) requires an external ADC converter.
• Can I connect this sensor module directly to an STM32 board?
  Yes, it is fully compatible with STM32 microcontrollers using 3.3V power and GPIO or ADC inputs.
• What supply voltage is required for the LM393 LDR Light Sensor Module?
  The module operates on a DC supply voltage range of 3.3V to 5V.
• Can I power this module directly from a 3.3V pin on my ESP32?
  Yes, the onboard LM393 comparator is fully functional and stable at 3.3V power.
• How much current does this light sensor module consume?
  The module draws very low current, typically around 15mA during active operation.
• What are the pin functions on the 4-pin LM393 LDR sensor module?
  The pins are VCC (3.3V-5V Power), GND (Ground), DO (Digital Switch Output), and AO (Analog Voltage Output).
• What is the difference between the 3-pin and 4-pin LDR light sensor modules?
  The 4-pin version includes both Digital (DO) and Analog (AO) outputs, whereas 3-pin versions only provide Digital Output.
• Do I need external resistors to wire this LDR module to Arduino?
  No, all pull-up resistors and LM393 comparator components are built directly onto the PCB.
• Do I need special libraries to code this LDR sensor in Arduino IDE?
  No special libraries are required; you can read inputs using standard digitalRead() or analogRead() functions.
• How do I adjust the trigger point for the digital output pin?
  Rotate the onboard blue potentiometer to adjust the light threshold at which the digital output (DO) switches logic states.
• Is example code available for MicroPython users?
  Yes, simple MicroPython scripts using machine.Pin and machine.ADC allow instant light level reading.
• Why is the Digital Output (DO) LED always ON or always OFF?
  The onboard potentiometer sensitivity threshold is likely set too high or too low for your current light level; turn it to recalibrate.
• Why are my analog readings jumping wildly?
  Check for a missing or loose common ground connection between the sensor module and your microcontroller board.
• Why does the digital output toggle continuously near the switching point?
  Rapid flickering light sources like 50Hz/60Hz AC bulb flickering can cause switching instability near the edge threshold.