LDR Light Sensor Module LM393 (3-Pin) Photosensitive Digital Switch for Arduino & ESP32

Specifications:

• Sensor Type: Photosensitive Resistor (LDR).
  
• Comparator IC: LM393 (Precision Digital Trigger).
  
• Pins: 3-Pin Header (VCC, GND, DO).
  
• Operating Voltage: 3.3V to 5V DC.
  
• Output Format: Digital (DO): Logic High/Low (Adjustable threshold).
  
• Indicator LEDs: Onboard Power (Red) and Signal Output (Green).
  
• Sensitivity: Adjustable via single-turn trimmer potentiometer.

Key Applications

• Day/Night Switch: The simplest way to trigger a relay for outdoor lighting.
  
• Security Alarms: Detect light changes when a door or drawer is opened.
  
• Object Counter: Use a steady light beam; the sensor triggers "High" every time the beam is broken.
  
• Energy Saver: Disable power-hungry peripherals on your IoT device when ambient light is available.

Project Evolution

• Past Projects: Ideal for users who have moved past basic delay-based coding and want to learn Interrupt Handling.
  
• Feature Upgrade: Unlike a raw LDR, this module handles the threshold logic on-board. This frees up your microcontroller's processing power and eliminates the need for Analog-to-Digital Conversion (ADC) pins.
  
• Effort/Requirements: Extremely Low. Connect 3 wires, set your potentiometer, and you are ready.

Virtual Technician & Wiring

⚠️ Probots™ Tech-Bridge ????: If the Green LED stays on regardless of light, turn the potentiometer counter-clockwise until it turns off, then adjust for your specific light level.

Package Includes:

1 x LDR Light Sensor Module LM393 (3-Pin) Photosensitive Digital Switch for Arduino & ESP32

Frequently Asked Questions (FAQ)

1. Does this board have an Analog output?
   No, this is the high-efficiency 3-pin version with Digital Output (DO) only.
2. Can I use this with an ESP32?
   Yes, it is fully compatible with 3.3V logic.
3. How do I set the "Darkness" trigger point?
   Adjust the onboard blue potentiometer until the Green LED triggers at your desired light level.
4. Why is the Digital Output reversed?
   Usually, DO is LOW when light is detected and HIGH when dark; check your code logic.
5. Can I drive a relay directly from DO?
   No, you should use the DO signal to trigger a transistor or a relay module.
6. What is the current consumption?
   Very low, typically under 15mA.
7. Is the LDR replaceable?
   It is soldered to the board, but can be desoldered if necessary.
8. Does it work with Raspberry Pi?
   Yes, it connects directly to any GPIO pin.
9. How do I know if the board is powered?
   The red power LED will light up as soon as VCC and GND are connected.
10. What is the Green LED for?
    It indicates the status of the Digital Output pin.
11. Is this module "Debounced"?
    The LM393 provides a clean switch, but rapid light changes will still reflect in the signal.
12. Can I use this outdoors?
    Only if protected from moisture and direct UV degradation.
13. What happens if I wire VCC to GND?
    The LM393 IC will likely be damaged.
14. Does it need a library?
    No library needed. Just use digitalRead().
15. What is the response time?
    Extremely fast (microsecond range).
16. Can I use 12V?
    No, the maximum safe voltage is 5V.
17. What is the screw hole size?
    3mm.
18. Can it detect IR light?
    It is primarily sensitive to the visible spectrum.
19. Will it trigger from a laser pointer?
    Yes, very effectively.
20. Is it Probots™ Logic-Safe?
    Yes, verified for 3.3V and 5V crossover projects.