LDR Light Sensor Module with Day/Night Invert Logic

LDR Photosensitive Light Sensor Module (LM393 Comparator)

The LDR Photosensitive Sensor Module is a versatile solution designed for projects requiring binary light detection (on/off) or analog light level measurement. It integrates a Photoresistor (LDR) with an LM393 high-precision voltage comparator to deliver reliable, threshold-based switching.

The module’s unique comparator circuit allows the user to define a precise light level using the onboard blue potentiometer. When the ambient light intensity drops below this calibrated threshold (i.e., it gets darker), the module's digital output (D0) switches LOW, providing a simple "Day/Night" or "Dark/Light" detection signal to your microcontroller. The module also exposes the Analog Output (A0) for projects that need to measure the variable light intensity.

🔧 Key 

• Sensor Component: High-sensitivity LDR (Photoresistor).
   
• Comparator:LM393 Dual Differential Comparator for stable switching.
   
• Dual Output: Simultaneous Analog (A0) and Digital (D0) outputs.
   
• Adjustable Sensitivity: Built-in potentiometer (trimmer) to set the trigger point.
   
• Output Logic:D0 is typically LOW when dark (configurable day/night trigger).
   
• Power Indicators: Includes Power LED (VCC) and Status LED (D0 output

💡 Applications

• Automatic Street Lights and smart outdoor lighting systems.
   
• Security Alarms (detecting sudden changes in light/darkness).
   
• Line Tracking Robots (used as a simple reflective sensor).
   
• Light Intensity Measurement for educational and monitoring projects

⚙️ Technical Specifications

                                                                   

Comparator Chip	**LM393**
Operating Voltage	**3.3V to 5V DC**
Output Type	Analog (A0) and Digital (D0)
Digital Output Logic	Low (0V) when light is below threshold (dark)
Sensitivity	**Adjustable** via Potentiometer
Operating Current (Typical)	$\approx 15 \text{mA}$
Typical Dimensions (L x W)	$\approx 32 \text{ mm} \times 14 \text{ mm}$
Interface Pins	VCC, GND, A0, D0 (4-Pin Header)

 

📦 Package Includes

• 1 × LDR Light Sensor Module with LM393 Comparator