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From: sow@luthcad.UUCP
Newsgroups: sci.electronics
Subject: Re: Stolen item-detectors (Was: Re: Laser eavesdropping)
Message-ID: <663@luthcad.UUCP>
Date: Sat, 11-Apr-87 05:08:39 EST
Article-I.D.: luthcad.663
Posted: Sat Apr 11 05:08:39 1987
Date-Received: Wed, 15-Apr-87 05:45:56 EST
References: <16143@sun.uucp> <2632@phri.UUCP> <1683@kitty.UUCP> <2634@phri.UUCP> <959@obelix.UUCP>
Reply-To: sow@luthcad.UUCP (Sven-Ove Westberg)
Organization: University of Lulea, Sweden
Lines: 20
Keywords: modulation

In article <959@obelix.UUCP> per-el@obelix.UUCP (Per Elmdahl) writes:
>In article <2634@phri.UUCP> roy@phri.UUCP (Roy Smith) writes:
>>	This is also, BTW, one of the ways those stolen-item detectors in
>>stores work.  The big plastic clips contain some sort of passive tuned
>>circuit, with a diode detector. 
>
>  A girlfriend of a friend of mine found one detector in a box she had
>got from a shop. I opened it and found a coil with about 10 turns and 
>a capacitator in it.

You will be even more puzzled, if tell you that you probably have
a lot of this coils already. They are hidden under some sort of
barcode markers. Most record stores use them. When you pay, you
got a marker with the text "paid" on the barcode marker, the paid
marker is some sort of shield. Peel of the paper and take a look.

Sven-Ove Westberg, CAD, University of Lulea, S-951 87 Lulea
Tel:     +46-920-91677  (work)         +46-920-48390  (home)
UUCP:    sow@luthcad.UUCP  or  seismo!mcvax!enea!luthcad!sow
ARPA:    enea!luthcad!sow@seismo.css.gov