Instructables
I found a bunch of PIR sensors on eBay. They are mounted on a pcb that was produced for a hands free set for mobile phones. I like to describe here how to prepare the sensor for the usage in robotics projects.

If you don't know what a PIR sensor is, just have a look at Wikipedia http://en.wikipedia.org/wiki/Passive_infrared_sensor . The product where the boards comes from can be bought here http://www.greasemonkeyconversions.com/10609/Com_N_Sense_Hands-Free_Kit_(Nokia_3310_etc).shtml . I bought the boards from a seller named "kalleb" on eBay. A search of the seller or for the subject "PIR INFRARED SENSOR" leads to the offer. He still offers some boards.

On the boards you can also find some switching voltage converters. I used them in an other project http://www.instructables.com/id/SLVOL8FFBGW8AF4/ where I needed to get +-15V out of a +5V supply. There are other useful components as well, but here we only need the pir sensor and the op amp that prepare the pir signal for direct usage with a microprocessor.

Step 1: What you need

First of all you need the pir board.

for preparation:
- a soldering iron
- tin-solder
- a jigsaw

for testing:
- a tabletop power supply with a +5V output (0.2A current is enough for testing)
- a voltage meter
- some wires
 
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scanada1 year ago
This is very interesting information. I've been building my robot for some time now and this has certainly opened some new paths. Thank you for posting it.
I got one of these FREE, yes FREE from my school caretaker and the old controller board because we had the alarm replaced.
fynflood6 years ago
That's some good info... What's the range on that little guy?
frickelkram (author)  fynflood6 years ago
About 1-25 cm without optics, have a look at step 3.
heh, shows how much I paid attention ; ) Thanks.
ferrocene6 years ago
Great info! I've been looking for an inexpensive way to do just this.

If you try optical lenses, make sure that they're transparent in the mid-IR that these sensors see. Glass isn't. Plastic lenses from a disposable camera might be, but I haven't checked. The polyethylene used to make the Fresnel lenses is, of course.

I'm considering buying a bunch of bare PIR sensors from Goldmine Electronics (www.goldmine-elec-products.com/prodinfo.asp?number=G9270). Assuming the part is what they say it is, it comes with a transistor preamp. Building an array of these, with some tiny op amps might make a nice lo-res camera!
frickelkram (author)  ferrocene6 years ago
Hi, I had a look at the sensors you are going to buy. As far as I understand it, this sensor need electronics to get a signal that can be used with microcontrollers. Every sensor I saw so far has a FET transistor build in. But that does not mean that you get a usable signal out of it.
You can use the schematic I send here to build a working sensor, but you have to build it on your own.
Before I bought this small boards I experimented with sensors. The signal that comes straight out of them is very small, only some mV.
Have a look here to find out how the electronics work.
http://optoelectronics.perkinelmer.com/content/ApplicationNotes/APP_PyroElectronics.pdf
AWESOME! I like all stuff like this, and I mean all. Cool Instructable!