KY-018 Photosensitive LDR Sensor Module

KY-018 Photosensitive LDR Sensor Module is an affordable and highly popular module that allows digital systems, such as microcontrollers, to easily detect and measure ambient light intensity. This compact unit centers around a Cadmium Sulfide (CdS) Photoresistor, or Light Dependent Resistor (LDR), whose electrical resistance consequently decreases proportionally as the light hitting its surface increases. The KY-018 is a three-pin module providing a digital output, making it exceptionally straightforward for hobbyists and professionals to integrate it directly into projects requiring light-based activation. Therefore, you can utilize this module for simple light-sensitive switches or as a component in automatic illumination systems where cost-effectiveness and rapid response are crucial design factors.

Key Features:

• High Sensitivity LDR: Features a high-quality LDR sensor that provides a wide range of resistance change across varying light levels, from darkness to bright illumination.
• Digital Output: The module includes an on-board comparator chip (often LM393), which allows the output to switch digitally based on a user-adjustable threshold.
• Adjustable Threshold: Users can set the switching sensitivity using the included precision trim potentiometer, optimizing the trigger point for specific environmental conditions.
• Low Power Consumption: This module maintains low power draw during operation, making it ideal for battery-powered or energy-efficient embedded systems.
• Standard KY-0xx Interface: The familiar 3-pin interface simplifies connection to common development boards like Arduino, ESP32, and Raspberry Pi.

Technical Specifications:

• Input Voltage (V_CC): 3.3 V to 5 V DC
• Output Type: Digital Switch Output (0 V / V_CC)
• LDR Type: Cadmium Sulfide (CdS) Photoresistor, 5mm diameter
• Dark Resistance: ≥ 1 MΩ
• Light Resistance (10 Lux): ≈ 5 – 10 kΩ
• Response Time: Typically 20 ms (rise time) and 30 ms (fall time)
• On-board Components: Comparator IC (e.g., LM393) and a Sensitivity Trim Potentiometer

Mechanical Specifications:

• PCB Material: FR-4 Fiberglass
• Module Dimensions: ≈ 15 mm x 35 mm
• Mounting Holes: Includes two standard mounting holes for secure attachment to enclosures or project platforms.
• Connector Interface: 3-pin male header (often 2.54 mm pitch)

Dimensions:

• Module Length: ≈ 35 mm
• Module Width: ≈ 15 mm
• Mounting Hole Diameter: ≈ 3 mm
• LDR Diameter: 5 mm
• Weight: ≈ 2 g (Extremely light)

Pinout and Wiring:

• Pin (S): This is the Digital Output pin. Connect this pin directly to a digital input pin on your microcontroller (e.g., Arduino’s D2).
• Pin (VCC): Apply the positive power supply (typically 5V or 3.3V) to this pin.
• Pin (GND): Connect this pin to the circuit ground (0 V).
• Wiring Note: The digital output goes HIGH when the detected light is below the threshold set by the potentiometer, and it goes LOW when the light is above the threshold. However, this behavior can vary slightly depending on the specific board version.

Datasheet Reference:

• Download Generic LDR Photoresistor Datasheet

Commonly Used in:

• Security Systems: Serving as basic presence or light-level trip sensors in alarms and monitoring devices.
• Robotics: Providing rudimentary light-seeking or light-avoiding capability for small autonomous robots.
• DIY Electronics Projects: A fundamental sensor for beginners learning about analog sensing and digital interfacing with microcontrollers.

Applications:

• Automatic Night Lights: The module automatically activates an LED or lamp when darkness falls below the set threshold.
• Ambient Light Dimmers: Systems use the output to adjust screen brightness or control ambient lighting intensity in a room.
• Counter and Tripwire: Developers use it to sense when an object blocks a light source (e.g., counting objects on a conveyor belt).

Equivalent Models:

• TCRT5000: While primarily a reflectance sensor, it offers a digital output based on light, similarly achieving basic light detection.
• KY-018 Analog Version: Some modules provide an analog voltage output rather than a digital switch, giving more granular light intensity data.
• BH1750FVI: A digital I²C light sensor that offers much higher precision (lux measurements), although it requires more complex coding.

Package Includes:

• 1 x KY-018 Photosensitive LDR Sensor Module