Infrared motion detector circuit

Infrared motion detector circuit

Infrared motion detector circuit


Here is the circuit diagram of an infrared motion detector that can be used to sense intrusions.Infra red rays reflected from a static object will be in one phase, and the rays reflected from a moving object will  be in another phase.The circuit uses this principle to sense the motion.

The IC1 (NE 555)  is wired as an astable multivibrator .The IR diode connected at the output of this IC produces infrared beams of frequency 5Khz.These beams are picked by the photo transistor Q1 .At normal condition ie; when there is no intrusion the output pin (7) of IC2 will be low.When there is an intrusion the phase of the reflected waveforms has a difference in phase and this phase difference will be picked by the IC2.Now the pin 7 of the IC 2 goes high to indicate the intrusion.An LED or a buzzer can be connected at the output of the IC to indicate the intrusion.

Circuit diagram with Parts list.


  • Comparators IC2a and IC2b are belonging to the same IC2  (LM1458).So the power supply is shown connected only once.No problem.
  • When there is disturbance in the air or vehicles passing nearby,the circuit may get false triggered.
  • POT R5 can be used for sensitivity adjustment.

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October 5, 2009 - Posted by | detector, project ideas |



    Comment by DEL | October 14, 2009

  2. i like ur projet work ,and i want to be a frend

    Comment by everest | October 16, 2009

  3. where the transmitter and receiver want to fit? if the transmitter is placed in a blind person means where we want fit the transmitter and how can we identify the opposite obstacle?

    Comment by meena | November 18, 2009

  4. how to connect pin no 7 of IC2b?

    Comment by deni | January 27, 2010

  5. please submit the project

    Comment by jared onderi | March 10, 2010

  6. respected sir,
    i want to make small flying robot with camera,so can u provide
    whole description of it,circuit diagram,block diagram completely and how much its cost send me this at my e-mail id
    thank you.

    Comment by dinesh raghuwanshi | March 21, 2010

  7. very good project

    Comment by mahmoud | March 23, 2010

  8. Hello,
    The capacitor symbol used in schematic is polaric capacitor, but available capacitors in this ratings are non polaric disc capacitors,
    So can i use non polaric disc capacitors instead?

    Comment by Aamir Shaikh | October 6, 2017

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