This PIR Sensor detects motion by measuring changes in the infrared (heat) levels emitted by surrounding objects. When motion is detected the build-in LED lights up the lens dome as a visual signal, and the module also outputs a high signal on its output pin.
This is the latest revision B version of this sensor, which includes the following improvements:
Longer detection range, selectable by an onboard jumper
Wider supply voltage, from 3 to 6 VDC
Higher output current provides for direct control of an external load