# Pir

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#### rasclerhys

##### New Member
Hi
I have a Pyroelectric Infra Red sensor module and i was wondering how it worked. i know that it has three legs one being the ground, the other being the source and the other being the drain. If i was to create a simple device that when you hover your hand in front of the PIR it turns on, how would i do it?
What legs do i connect to what?
Thanks

#### HarveyH42

##### Banned
Suggest searching the web, or getting the data sheet for you particular device. It's been a few years, but as I remember you need to amplify the signal coming off the module, and a few other things. The proper lens is also important to get much range out of it. I do remember a site that went through it pretty good a while back, but it seemed like a whole lot of work, compared to just modifying a security light.

#### rasclerhys

##### New Member
I have looked but can only find out how the PIR itself works not how to put it in a circuit.
Thanks

#### audioguru

##### Well-Known Member
It is a motion detector for warm mammals.
The IR detector detects heat and the fresnel lens causes changes in the amplitude of the signal when there is a warm object moving.

It probably will not detect a person wearing winter (insulating) clothing.

#### DirtyLude

##### Well-Known Member
You can put something together with a microcontroller or you can use some of the dedicated PIR sensor chips. You can find some on futurlec.

PIR Sensors

#### BrownOut

##### Banned
Not to go O/T, but my store-bought PID detectors are turning to be crap. I am beginning to become interested in building some custom units to replace the junk that's on the market.

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#### HarveyH42

##### Banned
Not to go O/T, but my store-bought PID detectors are turning to be crap. I am beginning to become interested in building some custom units to replace the junk that's on the market.

Quit buying Chinese stuff off E-Bay, might get better quality at home, good for the economy.

How Infrared Motion Detector Components Work

Lucky on vacation, and have plenty of time to search for stuff. This gives pretty good overview, theory, and schematic. There are also chips to handle most of it, but couldn't find them when I was interested, and before I figured the off-the-shelf stuff was a better choice.

#### HarveyH42

##### Banned
You can do PIR with a single microcontroller. Some have integrated OPAmps or sensitive enough ADC's. TI has an app note for interfacing a sensor with a MSP430F2013. Also Zilog sells an E-Pir sensor unit that is just one of the Z8 Encore!'s with a bare sensor and lens. There a schematic for it within the tech spec.

I have a few bare sensors and lenses that I've been meaning to play with here.

Never even occurred to me to try a sensor with a microcontroller. I lost interest in the raw sensors before I started with AVR. Might wire one up sometime, if I run across one. I know I saved some, but no clue where to even look.

#### rasclerhys

##### New Member
Oh i live in Britain,and we dont have RadioShack here.
I got it from a site called Bitsbox.co.uk
They have the info for the PIR just not a simple circuit, with an LED a battery and the PIR.

#### DirtyLude

##### Well-Known Member
Is this a bare sensor that you have or an actual module with a lens already on it? You have a pic or a link? I can't imagine them sending you a battery, LED, and a bare sensor in a kit.

If it's a module, then it would be easy to make up a simple schematic for you to show how to light the LED.

#### rasclerhys

##### New Member
Oh no they didnt send an LED etc, that is what i have, i just dont want to go using transistors. Here is the link:

Thanks

#### DirtyLude

##### Well-Known Member
That's a bare sensor. There is no simple circuit that will work for you. Those dedicated PIR chips are about the closest you will get.

The best solution if you want a simple circuit is to get a module like this one:
SparkFun Electronics - PIR Motion Sensor

#### rasclerhys

##### New Member
Ok Thanks

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