PIR Sensor

Passive Infrared sensor

A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.

A PIR(Passive Infrared) sensor is a motion detector which detects the heat (infrared) emitted naturally by humans and animals.When a person in the field of vision of the sensor moves, the sensor detects a sudden change in infrared energy and the sensor is triggered (activated).They are commonly used in security lighting and alarm systems in an indoor environment.The PIR sensors have a range of approximately 6 meters, depending on conditions.The sensor adjusts to slowly changing conditions that occur normally within the environment, but shows a high-output response when a sudden change takes place

pir sensor


Operating voltage 5V to 20V
Power Consumption 65 mA
TTL output 3.3V, 0V
Delay time Adjustable (.3 to 5min)
Sensing range about 120° and 7 meters

PIR Sensor pinout

PIR Sensor pinout

Hardware Connections

-->    Vcc to 5V of arduino

-->    Gnd to Gnd of arduino

-->    out to Digital pin 8(D8) of arduino

PIR Sensor working

PIR Sensor working

PIR Sensor Element

PIR Sensor Element

  • PIRs are basically made of a pyroelectric sensor, which can detect levels of infrared radiation.
  • Above figure of PIR element shows the round metal can with a rectangular crystal in the centre.
  • Every object emits some low-level radiation, and the hotter objects emits more radiations.
  • The PIR element is covered by lens to increase range of operation.

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