Light Dependent Resistors (LDRs) are little light sensors. As the squiggly face is exposed to more light, the resistance goes down. When its light, the resistance is about 5-10K ohms, when dark it goes up to 200K ohms.
These are the same KLDRs we use in our popular Edukit #2 Sensors.
To use, connect one side of the photocell (either one, it's symmetric) to power (for example 5V) and the other side to your microcontroller's analogue input pin. Then connect a 10K pull-down resistor from that analogue pin to ground. The voltage on the pin will be 2.5V or higher when it's light out, and near ground when it's dark.
Specification
- 5mm Diameter
- Resistance Decreases as the Light on the Device Increases
- Dark resistance: 1M ohm
- Resistance @ 10 Lux: 10-20k ohm
- Resistance @ 100 Lux: 2-4k ohm
- Max. voltage: 150V peak AC or DC
- Power dissipation: 100mW
- Lead pitch: 3mm
- Operating temperature: –30°C to +70°C
