The LDR Module (Light Dependent Resistor module) is a simple sensor board that detects light intensity and converts it into an electrical signal, making it easy to use with microcontrollers like Arduino, ESP32, or Raspberry Pi. 🔹 Details and Explanation Main Component: LDR (Light Dependent Resistor) – its resistance decreases when light increases and increases when light decreases. Working Voltage: 3.3V – 5V (depending on module design) Output Types: Analog Output (AO): Provides variable voltage proportional to light intensity. Digital Output (DO): Provides HIGH/LOW signal based on a threshold set by an onboard potentiometer. Comparator IC: Many modules use LM393 comparator to convert analog signal into digital output. Adjustable Sensitivity: A small potentiometer on the module lets you set the light threshold for switching DO. 🔹 Working Principle The LDR senses the surrounding light. Its resistance changes → converted into voltage signal. The module outputs: Analog value: Continuous range for measuring exact brightness. Digital value: ON/OFF based on threshold (e.g., for night/day detection). 🔹 Pins VCC: Power supply (3.3V or 5V) GND: Ground DO: Digital output (1 = light detected, 0 = dark) AO: Analog output (0–1023 on Arduino, depending on light level) 🔹 Applications Automatic street lights Light/dark sensors (day/night detection) Security systems (intrusion detection with laser + LDR) Robotics (line-following, obstacle detection with IR + LDR) Energy-saving devices (turning off/on devices based on light) 👉 Example: If you connect the AO pin to Arduino’s A0 analog input, you can measure brightness as a value between 0 (dark) and 1023 (bright). If you connect the DO pin to a digital input, you can trigger an LED or buzzer when light falls below a set level.