PIR Motion Detector/Sensor Circuit Diagram

Passive Infrared Sensor (PIR) is very useful module, used to build many kinds of Security Alarm Systems and Motion Detectors. It is called passive because it receives infrared, not emits. Basically PIR sensor detects any change in heat, and whenever it detects any change, its output PIN becomes HIGH. They are also referred as Pyroelectric or IR motion sensors.

Here we should note that every object emits some amount of infrared when heated. Human also emits infrared because of body heat. PIR sensors can detect small amount of variation in infrared. Whenever an object passes through the sensor range, it produces infrared because of the friction between air and object, and get caught by PIR.

The main component of PIR sensor is Pyroelectric sensor shown in figure (rectangular crystal behind the plastic cap). Along with this, BISS0001 ("Micro Power PIR Motion Detector IC"), some resistors, capacitors and other components used to build PIR sensor. BISS0001 IC take the input from sensor and does processing to make the output pin HIGH or LOW accordingly.

PIR Sensor

Pyroelectric sensor divide in two halves, when there is no motion, both halves remain in same state, means both senses the same level of infrared. As soon as somebody enters in first half, the infrared level of one half becomes greater than other, and this causes PIRs to react and makes the output pin high.

Pyroelectric sensor is covered by a plastic cap, which has array of many Fresnel Lens inside. These lenses are curved in such a manner so that sensor can cover a wide range.

We have built a very simple Motion detector circuit here. We are using a HC-SR501 PIR Sensor, an LED (which will glow whenever there is a motion infront of the sensor) and resistor. Vcc PIN of PIRs connected to the positive terminal of the 9v battery, GND pin is connected to negative terminal of battery and Output pin of PIR is connected to LED with a resistor of 220 Ohm. When there is any motion in the range of PIRs, LED will start blinking.


Circuit Components

  • PIR Sensor (we used HC-SR501)
  • Resistor 220ohm (any resistor below 1k ohm)
  • LED
  • Battery (5-9V)


Circuit Diagram and Explanation

PIR Motion Detector/Sensor Circuit Diagram

PIRs takes some time to stable itself according to surrounding conditions, so you can find, LED turn ON and OFF randomly for about 10-60 seconds.

Now when we find the LED blinking whenever there is any motion, look back of the PIR, you will find a jumper which is placed between outer corner PIN and middle PIN (see diagram above). This is called “non-retriggering” Or “Non-repeatable trigger” and jumper said to be in L position. In this position LED will blink continuously until there is motion.

Now if you connect this jumper between inner corner PIN and middle PIN, then LED will stay on all the time till there is any motion. This one is called “retriggering” or “Repeatable trigger” and jumper said to be in H position.

PIR Sensor Components

There are two potentiometers (shown in above figure), used to set the time delay and distance range. Time delay is the duration in which the LED will remain ON (out pin HIGH). In Non repeatable triggering, OUTPUT will become low automatically after the time delay. In Repeatable triggering OUTPUT will also become low after time delay, but if there is a continuous human activity; OUTPUT will remain HIGH even after the time delay.

Turn the Distance Adjustment potentiometer clockwise rotation, increased sensing distance (about 7 meters), on the other hand, the sensing distance decreases (about 3 meters).

Turn the Time delay potentiometer clockwise rotation sensor the delay lengthened (600S, 10 minutes), on the opposite side, shorten the delay (0.3 second).

Generally PIR detects infrared of 8 to 14 micrometre of wavelength and has range of 3-15 meters with a field of view less than 180 degrees. This range can vary upon different models. Some ceiling PIRs can cover 360 degrees. PIRs generally operate at 3-9V DC.


Comments (26)

  • Maddy's picture

    What is the range of a PIR sensor?

    Jun 09, 2015
  • Shivam Sahil's picture
    Shivam Sahil

    Most of them could detect upto 20 feet whereas some of them may go till 30 feet

    Sep 17, 2017
  • basith's picture

    sir ...this circuit also good

    but this is only active when human actions there's no actions or movement no response
    sir..I riqstng u
    I want a circuit tht active when human enterd and deactivate if human absantsts

    plz rply me soon as possible

    Jan 07, 2016
  • Jayant's picture

    I am not getting you, this circuit is already working as per your need. The LED/alarm gets only activated in human presence.

    Jan 14, 2016
  • ram's picture

    he is right, bcoz its activate on human motion capture, if there is a no movement and also person is present but not moving.then its get off after sated time

    Oct 16, 2016
  • Ediyo 's picture

    I wish to understand, can this circuit not be used in a room? What I mean is, in a room, you may have other things that generate heat light fan, refrigerator, TV set and you can also have an Air conditioner.

    In such a situation, can the system work very well? Or should it be limited to work only on passage ways and stair case?

    Jan 25, 2017
  • Enrico's picture

    sir..can you make it turn off when the person exits the room?
    for example:
    when the person enters the room, the sensor detect the person and turns on the light, and when the person gets out from the room, the sensor detect the person and turns off the light.
    im trying to make this for my bathroom light, can you help me?

    Feb 18, 2016
  • Awes's picture

    how to make,when pir detect motion then all alarm should ring continouse till we switch off and on pir circuit.

    it is because the pir ring buzzer for very short period.

    Feb 29, 2016
  • Maddy's picture

    Read the working of PIR sensor carefully, you can increase the Period by using the Time delay control knob.

    Mar 11, 2016
  • GOPINATH G's picture

    sir, In my PIR sensor the output pin always goes high even if there is no motion detected, I even tuned the sensitivity and delay,but i cant, plz help me !.........

    Feb 29, 2016
  • Sammy's picture


    I want that when my sensor detects it turns on the alarm and alarm should remain on till alarm 3-4 minutes.

    Jun 06, 2016
  • Maddy's picture

    You can set the time delay using Time delay potentiometer, upto 10 minutes. Please read the article carefully.

    Jun 11, 2016
  • VEERAMANI Ayyandurai's picture
    VEERAMANI Ayyandurai

    we are facing color wire interchanging problem in our process, we need correct color presence or not identification by using simple circuit,it is possible pls send me quote to my email id along with project details at soon.

    Jun 15, 2016
  • Mohan Kamadi's picture
    Mohan Kamadi

    SIr plz tell me the price of PIR sensor, And Where I purchase it.

    Sep 02, 2016
  • Guru 's picture

    simly go to amazon site then searh select and by

    Sep 18, 2016
  • Manzoor khan's picture
    Manzoor khan

    wtat is the range of pir sensor one pir sensor number of lights to connet

    Sep 07, 2016
  • sudeep mishra's picture
    sudeep mishra

    what will hppn if some small creature or animal in front of a sensor ???

    Oct 05, 2016
  • Didier's picture

    working range is 5m

    Nov 22, 2016
  • Sayeed Ahmed's picture
    Sayeed Ahmed

    Can I use 12V Battery???

    Dec 26, 2016
  • hmza's picture

    sir ...this circuit also good
    but this is only active when human actions there's no actions or movement no response
    sir..I requesting u
    I want a circuit that active when human entered and deactivate if human absense
    plz rply me soon as possible

    Apr 25, 2017
  • ashwini's picture

    motion sensor turns the light on if there is human action...but does not when human present in the room but without any movement...how to solve this issue ..how to write code for this ..??
    please reply as soon as possible..

    Jun 02, 2017
  • vince jack ludovice's picture
    vince jack ludovice

    can i use pcb for this circuit

    Aug 04, 2017
  • Nath.'s picture

    I have a question, does it work with a light and alarm or can it be connected to both?
    When someone enters, the light on and the alarm goes on as well,..
    And can it be connected on the fence of a house?

    Sep 06, 2017
  • B.Aswinth Raj's picture
    B.Aswinth Raj

    You can use the output pin of the sensor to drive any load you want. The load might be Light Alaram ar anything that you desire. But you should design apprpriate driver circuit for it.


    Sep 06, 2017

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