Pir Sensor Hc-Sr501 Motion Sensor

The pir (passive infra-red) sensor is a pyroelectric device that detects motion by measuring changes in the infrared (heat) levels emitted by surrounding objects. This motion can be detected by checking for a sudden change in the surrounding ir patterns. When motion is detected the pir sensor outputs a high signal on its output pin. This logic signal can be read by a microcontroller or used to drive a transistor to switch a higher current load.