IR Sensors

[koossa]

Good day Picers!!

I've got a relatively small amount on knowledge with IR Sensors.
I want to build a motion detector system where I put 2 sensors about 1m appart from each other and connect them to a PIC.
If both of them are triggered, I want to activate an alarm.

Is it better to build my own sensor system using 2 separte sensor components or easier to use 2 fully compiled sensor units for this project?

Thank you
Koossa

[BrianT]

You talk of a "motion sensor". Do you mean a human presence/absence detector or a velocity measurement system.

If you are looking for humans, the easiest is to buy two ready to go PIR (Passive Infra Red) sensors. These are $10 and up and give a saturating transistor as the output. Harder to use, but more versatile, are the $30 thermopiles from companies like Melexis (which I use). Thermopiles can measure temperature remotely while the PIR style just detect a thermal anomaly and turn on the output transistor.
The thermopile approach requires you to build a reasonably sophisticated high impedance, very low leakage op amp circuit.

Tell me more about what you are trying to do and I can explain further.

HTH
Brian

[koossa]

Hi Brian

Thank you very much for your feedback!

Yes, I am talking about human presence/absence detector.
I just need something that will be reliable and it's for outdoor purposes (for security).

Do I need 2 sensors, or will one be reliable enough?

Thx a lot!!
koossa

[grounded]

Koossa I use PIR motion sensor with PIC chip for game cams the PIR I uses is about $10.00 and gives a 5v output I add a 10k pull down resistor that I use to trigger a Interrupt and operates the cam.
I get them from electronics123 I think the item # is cps76 kc7783 PIR detector

here's a link to some of my stuff
http://community.webshots.com/user/richardslaton
If I can help let me know
grounded

[koossa]

Thank you very much Grounded, I will take a look!!

[koossa]

Hi Picers!!

I want to use this motion detector for security purposes (detect human motion)

When putting a fresnal lens over the PIR Motion sensor it increases the detection distance.

Without the lens I will get about 10 feet detection distance and with it about 20 yards.

My question is, will the motion detection be more reliable without the lens if I only need 10 feet detection distance?

Thank you very much!!
Koossa

[grounded]

from my dealings using PIR 's they are very unstable with out the lens
do a search on the web they make a lot of lens wide angel, long range etc.
and diffrent focul lenghts.

[koossa]

Thank you very much Grounded!!

[koossa]

Grounded

According to the electronics123 catalog the "PIR Movement Detector Module" (KC7783) has a fresnel lens already integrated.

Here is a piece of their description:

"A pyroelectric sensor module which is developed for human body detection. A PIR detector with a fresnel lens are mounted on a compact PCB tohether with an analog IC...."

The detection range is 3 meters, do you think this module will be reliable if I connect it to a pic without any additional fresnel lenses?

Thank you koossa

[grounded]

yes it does. what testing I did with the factory lens it work fine but did not have the distance I need the little lens just pops off and I set it up with a new lens and I get 20 yards. I think they are used by a of lot robot builders you mite check some of there forums. the range they use is more like what you need.
if I can help let me know
grounded