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Project Help and Ideas » I hate PIR sensors... other options?

October 20, 2011
by scottmc94
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My PI sensor seems to go off randomly all the time. What I am wanting is to catch when someone breaks a plane, like walks through a door or something.

Anyone have any ideas for a different type of sensor? If possible I would prefer not to have to wire both sides, like I would not want to do a garage door safety sensor for example.

Thanks for any ideas.

October 21, 2011
by Ralphxyz
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Are you using a PIR (Passive Infra-Red Sensor) like this one from Parallex?

What is your range? Could you use an actual interrupted beam?

Possible combining an interrupted beam with the PIR would prevent false readings.

Ralph

October 21, 2011
by scottmc94
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Yes, I am using the one from Parallex.

Literally, I am wanting to catch when someone goes through a door, so an interrupted beam would be fine, but I just didn't want to have to run wires across the threshold or put up a sensor on the other side of the door.

What started this.... Last night I was working on the led marque and my fingers were starting to get sore from the wire twisting, and the wife comes in the room. "It would be fun to scare someone with lights and sound when they enter a room" and then she left.

I thought, sure no problem. So I stopped working on the marque, sat down at the breadboard. Put 4 LEDS, a piezo buzzer and the PIR sensor on and then wrote and downloaded the code. 30 minutes later it was working, and I took it downstairs and set it up in the bathroom.

We were watching TV and I kept hearing the buzzer go off, but she didn't notice... After a bit she walked in the bathroom and it worked fine and buzzed and lighted, she enjoyed it, but she didn't realize it had been going on and off sporadically the whole time and I was wondering if there was a better solution or something.

October 21, 2011
by rajabalu21
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I have used a laser (the cheap ones you can get from dollar stores), reflective strip/mirror, and a photo diode. The laser and photo diode are on the same side of the door the reflective strip (mirror) has a peel off backing that can we used like a sticker on the other side of the door frame. The angle of the laser should be adjusted such that the reflected laser beam falls on photo diode. This way all wires are on one side of the door.

Here is another link based on refection from the object that crossed the path.

-Raja

October 21, 2011
by scottmc94
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Thanks for that link Raja, I will look at it.

October 25, 2011
by scottmc94
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I bit the bullet and bought a Ping))) sensor. It is awesome and worked like a charm. It's 3x the cost, but the wife is happy, so it's worth it! lol

October 27, 2011
by Ralphxyz
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Ping))) sensor

When items are referenced it is nice to have a link, of course one can just about Google anything, as I did.

Looks like a neat device.

Ralph

October 27, 2011
by scottmc94
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Yeah, yeah, :) I will try to remember next time. It was really too much for this project, but you can do the math and actually know how many inches something is away from the sensor. I was surprised at how accurate it actually was.

Scott

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