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From: ccrse@ucdavis.UUCP (0058)
Newsgroups: net.consumers
Subject: Re: Infra-red /microwave detectors; for use as exterior people detectors
Message-ID: <36@ucdavis.UUCP>
Date: Mon, 13-Jan-86 13:20:11 EST
Article-I.D.: ucdavis.36
Posted: Mon Jan 13 13:20:11 1986
Date-Received: Tue, 14-Jan-86 03:47:39 EST
References: <211@hropus.UUCP>
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Organization: University of California, Davis
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> 1).  RADIO SHACK: infrared detector, cost about $70.  Disadvantages
> are, that its power input is 12V (not sure if A.C. or D.C.), and it
> has contacts for an alarm as output, so I would need some sort of relay
> to control the light...
> 
> ...The infrared units seem to be ideal, supposedly triggered by
> specific body temperature of a person (although I wonder about
> the effects of a hot summer or freezing winter night; I mean, your
> normal skin temp is about 85 - will the detector see anything if it's
> 90 degrees out???  Or if it's 10 degrees with the wind blowing, will
> you still give off sufficient heat?
 
I have had some experience with the RS IR motion detector.  From what
I've seen, I can tell you that, yes, they tend to be more sensitive when
the difference between air and body temperature is larger.  In a cold room,
for example, the sensitivity may be nearly double that in a heated room.
One thing which I *don't* know is if they detect bodies warmer than their
surroundings, or if they detect things that are a significantly different
temperature from their surroundings, whether higher or lower.  I would hope
for the latter, but tend to suspect the former to be true.

> The store detectors that open doors seem to have potential,
> unless their maximum range is 10 feet, in which case placement
> becomes very critical, and I might need more than one a some of the sides
> of the house.  Does anyone know who carries something like this???
> (If no one replies, I guess I'll just ask my supermarket manager).

You can get both types of motion detector from Dick Smith Electronics.
They carry what appears to be a better IR detector than Radio Shaft's
for $60.00, and a microwave unit for $70.00.  The microwave unit is listed
as having a max range of 25', both work off of 12 VDC and have adjustable
sensitivity. I have dealt with DSE a couple of times and had good experiences
so far.  They have stores in the bay area and LA, but seem to work mostly
through mail order.  They can be contacted by phone at (415) 368-1066
(inquiries) 1-800-332 5373 (orders), or by mail at 390 Convention Center Way,
Redwood City, CA 94073.