LDR(Light Dependent Resistor) also known as photoresistor is a resistor whose resistance varies with the amount of light falling on it. This is a large size LDR with a size of 12mm. To use, connect one side of the photo cell (either one, its symmetric) to power (for example 5V) and the other side to your microcontroller’s analog input pin. Then connect a 10K pull-down resistor from that analog pin to ground. The voltage on the pin will be 2.5V or higher when its light out and near ground when its dark. This sensor can be used for making a light sensor, color sensor, object sensor, line sensor, etc. Analog Applications:- Camera exposure control Auto slide focus – dual cell Photocopy machines – the density of the toner Colorimetric test Equipment Densitometer Electronics scales – dual cell Automatic gain control – modulated light source Automated rearview mirror Digital Applications:- Automatic headlight dimmer Nightlight control Oil burner flame out Streetlight control Absence/presence (beam breaker) Position sensor Other applications:- Annunciator Camera automatic photometry Electronic toy Industrial control Light control Light control lamp Photoelectric control Switch Specifications and Features:- Diameter : 12mm Number of Pins : 2 Dark resistance : max. 20MΩ Spectral Peak : 560nm Light Resistance (10 lux) : 10 – 20 kΩ Maximum Voltage : 250VDC Maximum Power : 0.2W Operating Temperature : -30˚C to 70˚C Response Time(μS) : 20(Rise), 30 (Down) Resistance Illumination : 3
