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
|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
PIR Sensor working
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.