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how can i make a motion sensor?????????????????????????????????????????????????????????????????????????????????????????? Answered



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.


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.

Circuit diagram with Parts list


When copying an answer directly from someone else's website is polite,and legally correct to cite exactly where you have aquired it from.


i wish instructables had a 'like' button.... :P

He he
JUdging by the watermark on the circuit diagram, its been lifted lock, stock and barrel from "www.circuitstoday.com"

Yeah i had a look there... :) It says exactly the same.. :P
Here's the link if anyone's interested. http://www.circuitstoday.com/infrared-motion-detector-circuit
But its again a short distance thing. I'm patiently searching for a wide angle long distant motion detection thingy to look down the hill for leopards.... :P
Help me if youve got time.. :P

**Roar!!!** http://1.bp.blogspot.com/_2-51K9qDJBY/TRQ5kk-A_DI/AAAAAAAAAiI/_BiQhyjOlG8/s1600/leopard-sleeping-in-tree.jpg

A unique problem you have there Pranav ;-)

Well the circuit he posted is only a beam-break sensor. What about a PIR instead ?
The operating principle of the circuit cited is complete tosh.


LOL I'm sure quite unique here on instructables.. :P

Well I have a silly PIR out there and positioned quite well but it hardly covers 3m forget the 10m it promises..... I have started to not like PIRs.... Do you think it could be this one thats a problem? maybe they do work better...

You can get narrow angle PIR that might suit you ? 10metre range is pretty standard for such things though, maybe you have a duff one ?


Hmmmm..... I think I DO have a crappy thing. :P I wouldnt doubt really...
Thanks! :)

Tricky to build - Buy one of THESE.
Apply 5V to the supply wires and when it sees a warm body pass by you'll get a pulse of several seconds on the third wire.  What are you trying to trigger from it?

Hold on - Are you saying you already have the sensor in the picture? What are you trying to do with it? (Preferably explained in standard English.)