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From: ee5391aa@hydra.unm.edu (Duke McMullan n5gax)
Newsgroups: sci.electronics
Subject: Re: motion detectors
Message-ID: <1990Aug1.020030.23775@ariel.unm.edu>
Date: 1 Aug 90 02:00:30 GMT
References: <4315@hazel13.UUCP>
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Organization: University of New Mexico, Albuquerque
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In article <4315@hazel13.UUCP> sirakide@motcid.UUCP (Dean Sirakides) writes:
>I'm toying with the idea of putting some small motion 
>detectors throughout my house in key locations.  I hope
...
>Does anyone have an idea of a manufacturer/model/source
>that might work for my purpose?
>Any idea what the interface is like?
>Any idea of price?
>Anybody had any luck with the idea already?

Dean, I've had success with the IR motion detectors used for outdoor lights.
I can pick up the unit at the local Price Club for $16, and although the DMM
showed the electronics working on 16VDC, it seems to run fine on 12VDC.

I have one mounted on a small plastic box, which contains a driver transistor
and a relay for switching the 12V. With a small but loud siren attached, it
makes a fine area-coverage (volume-coverage, actually ;^) burglar alarm.

Right now, I'm building three complete alarm units for a local engineering
firm.

The original interface is an optoisolater. I replaced it with an LED for ex-
perimental purposes, and added the transistor/relay later on when I put it in
a box. That optoisolater switched the gate of a triac, which I removed, they
being of limited use with DC.

My experience is that they're damn hard to approach undetected. In a very hot
room (~ body temp) they become considerably less sensitive, but you'd expect
that.

There's no distance parameter available, just the detect/nondetect line. In
this particular model, the output line asserts and remains so for about five
seconds after the motion ceases or moves out of range of the sensor head.

When the phase of the moon is right, it proves consistently sensitive at over
fifty feet (that's in cold weather).

Try it. It's cheap; it's widely available; it may be just what you need.


					Best o' luck,
						d

PS: I didn't make this clear: I REMOVE all the high voltage circuitry and
the lamp sockets, etc. Bend it 'till it fits.

						d


--
     "...above all shadows rides the sun, and stars forever dwell...."
						- J.R.R. Tolkien
   Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu