Adafruit Photo cell (CdS photoresistor) [ADA161]

Description

CdS cells are little light sensors. As the squiggly face is exposed to more light,the resistance goes down. When its light, the resistance is about ~1KΩ,when dark it goes up to ~10KΩ. 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. For a full tutorial with wiring diagrams,code examples and project ideas,please read the photocell tutorial page!