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From: ijk@hropus.UUCP (Ihor J. Kinal)
Newsgroups: net.consumers
Subject: Infra-red /microwave detectors; for use as exterior people detectors
Message-ID: <211@hropus.UUCP>
Date: Fri, 10-Jan-86 14:34:27 EST
Article-I.D.: hropus.211
Posted: Fri Jan 10 14:34:27 1986
Date-Received: Sat, 11-Jan-86 07:02:18 EST
Distribution: na
Organization: Bell Labs, Holmdel, NJ
Lines: 52
Keywords: BURGLARS

I was wondering is anyone had the inside track on infrared detectors
or microwave detectors (e.g., those little units at supermarkets that
open doors).  I would like to hook one up on the outside of my house.
I figure this would greatly discourage vandalism and petty theft
(last year, someone stole Xmas lights off our tree outside, plus a 
bug-whacker light); but most important, would greatly discourage burglars
to have a side of the house light up as they approached (yes, I do realize
that many burglaries occur during the day, but that's another story).

I'm looking for something relatively inexpensive, since I would want to
install several (one on each side of the house, plus my back porch
makes at least 5).  The ONLY devices I've seen are

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. 

2).  HEATHKIT: complete kit includes two spotlights.  Obvious advantage-
just replace current outside lights, and leave them on.  Disadvantage,
is that the cost is about $170.

3).  Another alternative might be these sound switches that activate
lights.  I've got a couple inside the house, and they're OK, but
I'm not sure how water-resistant they are.  With an infrared detector,
I could presumably put it inside a plastic box (I hope infrared passes
thru clear plastic - anyone know for sure??????????????) and rest
easier.  Also, a burglar would presumably be very queit; I might
have to turn the sensitivity way up, and have it triggered by street
noise, air conditioner, etc.  While I don't mind occasional spurious
triggers (I'm not activating the burglar alram, just some powerful
lights), I don't want flashing lights to turn my house into a Xmas
tree year round.

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?

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).

Anyone thoughts on this subject would be greatly appreciated.
Thanx.

Ihor Kinal
houxm!hropus!ijk