15 January 2014 User ReviewCheck your delivery options:
PIR sensors are used to detect motion, it detects the movement of humans within the sensor range. They have pyro-electric sensor to detect infrared radiation and supporting circuitry, resistors and capacitors. The radiation emitted by a body is proportional to the temperature level of the body. They are small in size, consume less power, low cost. PIR sensor has two halves which are made up of material sensitive to the IR. The amount of radiation sensed by both slots is same when the sensor is idle but when hotter temperature bodies like human beings or animal passes near-by ,any one of the halves detects and thereby making a difference in the IR sensed by both slots which creates an output.
Most of the sensors use BISS0001 chip which emit a digital output from an analog sensor.