Let's Make Robots!

PIR (Passive Infrared Sensor)

Vendor's Description: 

PIR's are cheap little things that combined with a little chip (PIR Sensor Control IC) and possible a Fresnel Lens will tell you if there is motion in font of it. Especially that of a human body, as it is reacting on Infra Red.

You can not use a PIR for anything but on something that stands still, to detect something else that moves.

No, you cannot use a PIR to make a robot follow you. The PIR only detects changes. A moving robot (even turning it's head) would be one constant "alarm" of "changes" - not possible to tell what is what.

If you want to make a robot follow you, you either have to use a camera and some serious calculations, or something like the devantech Thermopile array sensors or hack an Infrared thermometer (often refered to as a Laser thermometer asthey often come with a guiding laser-beam).. or something else :D

PIR's can only detect changes! A moving robot will detect changes all the time! 


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This video by Jeri Ellsworth shows a (new to me) way to use a PIR sensor to detect heat (from a soldering iron). The link jumps straight to the part that discusses the PIR.

Notice how she explains:
- it has an analogue output
- PIR consists of two parts
- both parts try to cancel each other out
- she covers one part to hinder the self-balancing act

(I asked her to join us on LMR, no response so far)

http://www.ladyada.net/learn/sensors/pir.html has a very detailed explaination of the Passive Infra Red motion detector. And a complete "How to use" guide.

Lady Ada seems to have her own site that is funded and supported by the company she founded. It would certainly be cool to have her as an LMR member, but perhaps she'd feel it might draw potential traffic away from her own site.

Of course, if someone were to invite her to participate as another respected robotics vendor, maybe she would consider it.

Oh yes!
thanks guys
if there are 4 pins that means 2 are power and the others would be out and input right?

The datasheet for that PIR is here: http://www.futurlec.com/PIR_Module_B.shtml

The pins (from left to right on you picture above) are: VCC, GND, CDS, OUT.

Looking more closely at the image, they are actually labelled on the pcb. 

pir sensorhorray it worked, but how do i put in the data sheet?

im sorry for my comments earlyer it was uncalled for

way to be friendly ,not my fault im not as good as you at using the site! might be a resault of me having a life!