KY-018 Light Sensor – Measure Light Intensity with Arduino and Microcontrollers

Analog Module with Photoresistor for Automatic Lighting, Robotics and Monitoring Systems

The KY-018 Light Dependent Resistor (LDR) sensor module is a simple but effective ambient light sensor that changes resistance based on light intensity. It’s designed for easy integration with microcontrollers such as Arduino, ESP32, Raspberry Pi, and others, making it ideal for light-sensitive projects, automatic lighting, and educational electronics.

 Key Features

• Sensor Type: LDR (Light Dependent Resistor) – resistance decreases in bright light and increases in darkness.

• Operating Voltage: 3.3 V – 5 V DC – compatible with standard microcontroller logic levels.

• Pins: Generally a 3-pin interface (VCC, GND, S / A0) for easy wiring.

• Analog Output: Voltage output changes with light intensity, readable by analog inputs.

• Simple to Use: No special libraries needed — just read analog values.

 Overview

The LDR in the module forms a voltage divider with an onboard resistor. As light intensity varies, the voltage at the output pin changes proportionally. This signal can be read by an ADC on your microcontroller (e.g., Arduino A0) to determine ambient light levels.

 Typical Applications

• Automatic light control systems (turn lights on/off based on brightness).

• Environmental light monitoring for data logging or display.

• Robotics and automation reacting to light changes.

• Educational electronics and prototyping.

  
  

• According to the spectral characteristics of the photoresistor has three photoresistor: Ultraviolet photosensitive resistance, infrared light-sensitive resistors, Visible photosensitive resistance;
• The main parameters are as follows:
  A>. dark current, dark resistance: photosensitive resistance at a certain applied voltage, when the light is not irradiated when the flowing Current is called dark current. Applied voltage and dark current ratio as the dark resistance;
  B>. Sensitivity: Sensitivity is irradiated by light sensitive resistor, the resistance value (dark resistance) when irradiated with light Resistance value (light resistance) the relative change in values.
  C>. volt-ampere characteristic curve. Voltage characteristic curves are used to describe the resistance of the applied voltage and the photosensitive photocurrent relationship, On the photosensitive devices, the light current with applied voltage increases.
  D>. temperature coefficient. Photoelectric effect photoresistor affected by temperature, at a low temperature portion photoresistor photoelectric Sensitive high sensitivity at high temperatures is low.
  E>. rated power. Photosensitive resistor rated power is allowed for certain lines in the power consumed when the temperature rise High, its power consumption is reduced.