Photoresistors: Light-Sensitive Components Explained

What Are Photoresistors?

Photoresistors (LDRs - Light Dependent Resistors) are semiconductor devices whose resistance decreases when exposed to light. Made from high-resistance materials like cadmium sulfide, they act as "light-controlled variable resistors."

Main Classifications

1. Intrinsic Photoresistors

   • Pure semiconductor materials (e.g., silicon)

   • Require strong light for activation

   • Used in precision light measurement

2. Extrinsic Photoresistors

   • Doped with impurities to enhance sensitivity

   • Respond to specific light wavelengths

   • Common in infrared detection

3. By Spectral Response

   • Visible-light LDRs (400-700nm) for general purposes

   • Infrared LDRs (>700nm) for remote controls

   • Ultraviolet LDRs (<400nm) for sterilization systems

Key Applications

• Automatic Lighting: Streetlights, garden lamps

• Security Systems: Intruder detection via light breaks

• Camera Exposure Control: In vintage analog cameras

• Industrial Automation: Conveyor belt object counting

• Consumer Electronics: Tablet brightness adjustment

• Agricultural Tech: Greenhouse light monitoring

Why Choose Photoresistors?

✔ Low-cost
✔ Simple circuitry
✔ No moving parts
✔ Wide resistance range (1kΩ-10MΩ)

Modern LDRs now feature faster response times (<20ms) and improved durability, expanding their use in IoT devices and smart home systems.

Buy high quality LDRs online: https://www.sicubeshop.com