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From: pwh@bradley.bradley.edu (Pete Hartman)
Newsgroups: sci.electronics
Subject: Re: Anti-shoplifting devices
Message-ID: <1991May10.031735.1119@bradley.bradley.edu>
Date: 10 May 91 03:17:35 GMT
References: <050691.224256WDBURNS%MTUS5.BITNET> <19934@slice.ooc.uva.nl> <1991May9.135021.22131@sparrms.ists.ca> <1991May10.003238.24277@comp.vuw.ac.nz>
Distribution: usa
Organization: Bradley University
Lines: 17

In <1991May10.003238.24277@comp.vuw.ac.nz> cyborg@kauri.vuw.ac.nz (Alex Ivopol) writes:
[ description of sticker device to foil shoplifters ]
>This whole arrangement looks very much like a capacitor in parallel with a coil
>Don't ask me how it works tho...  I realize that this would most probably
>resonate in an electromagnetic field of the right frequency, but how does one
>disable it once you bought the product and go out the shop through the gates ?
>The sticker is diposable and stays on the merchandise once you bought it. The
>salespersons do not do anything funny with the products (like placing them
>briefly under the counter) before handing them back to you...

I don't remember precisely, but I took one of these apart some time ago,
and noticed that there was a puncturing of some sort that shorted the
capacitance.  I don't recall quite how it was produced, but it was
clearly not there in the store.
-- 
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Pete Hartman		  Bradley University		pwh@bradley.bradley.edu