Photoresistor LDR

The Photoresistor LDR (Light Dependent Resistor) is a variable resistor whose resistance changes with the light intensity that falls upon it. It is widely used in light sensing applications and projects where detecting light levels is essential. LDRs are cost-effective, easy to use, and suitable for various electronic projects, including light meters, street lights, and other light-sensitive devices.

Key Features:

• Light Sensitivity: Resistance decreases with increasing light intensity
• Simple Interface: Easy to integrate with microcontrollers and analog circuits
• Low Cost: Economical solution for light detection
• Wide Range of Light Detection: Can detect various light levels from low to high intensity
• Compact Size: Fits easily into small projects

Technical Specifications:

• Resistance in Darkness: Typically 1MΩ (depending on specific model)
• Resistance in Bright Light: Typically 10-20kΩ (depending on specific model)
• Spectral Peak: Approximately 540nm (most sensitive to green light)
• Response Time: Rise time ~20ms, fall time ~30ms
• Operating Temperature Range: -30°C to +70°C
• Diameter: Typically 5mm to 10mm (depending on specific model)

Applications:

• Light Meters: Measure light intensity for photography and scientific applications.
• Street Lights: Automatic on/off control based on ambient light levels.
• Alarm Systems: Detect changes in light levels for security purposes.
• Consumer Electronics: Light-sensitive control in devices like clocks and displays.
• Educational Projects: Common component in learning modules for electronics.

Usage:

1. Circuit Integration: Connect the LDR in a voltage divider circuit with a fixed resistor to create a variable voltage output based on light intensity.
2. Microcontroller Interface: Read the voltage output from the LDR circuit using an analog input pin on a microcontroller.
3. Programming: Write code to interpret the analog signal and perform actions based on light levels (e.g., turning on an LED when it gets dark).
4. Testing: Calibrate the LDR circuit for the desired light sensitivity by adjusting the fixed resistor value.

Caution:

• Environment: Avoid exposure to extreme temperatures and humidity, which may affect the LDR’s performance.
• Handling: Handle with care to avoid damaging the sensitive surface of the LDR.

Datasheet:
For detailed technical specifications, refer to the Photoresistor LDR Datasheet.