PIR sensor

I am having big problems to interface HW with arduino - this time with PIR sensor.

I have this sensor: http://si.farnell.com/jsp/search/productdetail.jsp?SKU=1006207

But I can't get any output from it. If I plug it in analog port I get a constant output from 300 to 500 but it doesn't change with motion. Question is do I need a lens to test this or should it work without? I just connected ground, 5V and output - no resistors or anything.

OK so you might just have blown it up.

Have you looked at the data sheet?

On page 8 there is a schematic for detecting humans. There is a lot of electronics round it. The output is tiny 3.3mV so you can't use it directly into the Arduino. Just feed what is going into Pin 2 of the micro computer into the Arduino, you don't need the circuit to the right of it.

What mico compuer? That schematic is totaly idiotic (elements are too close to each other). And isn't there any simpler way of connecting that to arduino?

Yes I looked at the datasheet! ;D

What mico compuer?

The rectangular box that covers the height of the circuit.

That schematic is totaly idiotic

Your opinion.

elements are too close to each other

Well re draw it with them further apart.

And isn't there any simpler way of connecting that to arduino?

No.

Found something - on a circut that used one of this PIR sensors.

It is a LM324N operational amplifier - any chances that this could be used?

Why don't you just use a pre-built module? They're relatively cheap and then you don't have to worry about all of the electronics necessary to make the sensor work correctly.

Here's one from Sparkfun: http://www.sparkfun.com/commerce/product_info.php?products_id=8630

Here's a couple from Futurlec (scroll down past the discrete sensors): http://www.futurlec.com/PIR_Sensors.shtml

Simply because I don't have them!

I am not trying to do anything with them - I just want to try them for fun! I got three of them for 4?.

Well you're not going to be able to do much with them without all of the support circuitry shown in the datasheet and a good understanding of analog electronics.

Then I will put them in a box and wait a few years ;D!