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From: esupg@warwick.ac.uk (Andrew Bargery)
Newsgroups: sci.electronics
Subject: Re: Car alarms(late idea)
Message-ID: <02~_0R|@warwick.ac.uk>
Date: 15 Apr 91 16:06:07 GMT
References: <1991Apr14.224844.3126@coral.bucknell.edu>
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hmm, I appear to have missed the discussion of car alarms first time round, so
I hope no one has already said the following. If they have, sorry.

One "new" alarm that has recently appeared here is a stand alone unit that
sits on the dash. It works by air pressure - when some opens the door they set
it off. Another one is an ultrasonic system (I think) incorporated in a teddy
bear that sits on the rear shelf. Both these systems seem 'neat' but I
don't see them being much good. You could probably reduce the sound to an
acceptable level by just wrapping a coat around device. Or throwing out of the
window. But maybe they deter joyriders...

Some of my favorite ideas however, are a little sneakier...

I saw a design in an electronics magazine that connected to the contact
breaker. It was based around a tacho chip that remained inactive for the first
few seconds, then it cuts in and cuts the supply to the CB if the revs go
above ~1500. Hence the thief can start the car, think he's done it, then he
tries to pull away....

In a similar vein, I beleive there are kits that allow you to place a valve in
the petrol line. The fuel in the carb. allows the car to be started, then
it cuts out and wont restart....

However, my personal favorite to ensure your car is there when you get back:
(I don't know if any one has actually tried this...)
With the increased use of ECUs in cars, why not have the software encoded by a
DES algorithm? Unless you know the password, it's going to be
just-a-little-tricky to hot wire :-)

------------------------------ esupg@uk.ac.warwick.cu -----------------------
         _____      Andrew     University of Warwick, Coventry, UK.
        /__|__\__    Bargery   154 Brunswick St, Leamington, CV31 2ER, UK.
     **=`()====()"             vox : +44 926 881264
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DISCLAIMER: I only drive to get from A to B. Very quickly.