What is a PIR (Passive Infrared) Sensor?
A passive infrared sensor (PIR) is an electronic sensor which is used to detect motion. The sensor measures infrared (IR) light radiating from objects in its field of view. Mainly they have used in PIR based motion detectors.
When a person in the field of the sensor moves, it detects a sudden change in infrared energy and the sensor is triggered (activated). It acts as a switch.
They don’t detect or measure Heat, but they detect infrared radiation emitted from objects.
These sensors commonly used in security, lighting, and alarm systems.
The range of PIR sensors is approximately 6 meters, depending on conditions.
PIR Sensor Pinout
|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|
- Vcc to 5V of Arduino.
- GND to GND of Arduino.
- OUT to Digital pin 8(D8) of Arduino.
How PIR Sensor Works
When PIR detects a motion of any object the output voltage is high because of its sense infrared radiation whereas it is low when there is no motion.
- PIRs are made of pyroelectric sensors which can use to detect levels of infrared radiation.
- In the above image, PIR has a round metal can in which there is a rectangular crystal in the center.
Uses / Applications
- Automatic Doors which open and close on Motion Detection.
- All Outdoor Lights.
- Lift Lobby.
- Motion Cameras.
- Lights on/off by Motion Detection.
- Basement Parking Areas.
- Escalator Lights(Staircase).
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