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Article #2937Re: How do anti-theft systems in Shops work ???
From: Bill Squire
Date: Wed, 15 Apr 1992 22:38
Date: Wed, 15 Apr 1992 22:38
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The type you got is a half wavelength at about 915 MHz and has a
magnetisable ferrite backing. If the ferrite is magnetised it is inessence
not there and will reflect at 915 MHz (like radar chaff). If the ferrite
is demagnetised it will either lower the freq or asorb it or both. To
defeat this system it stands to reason you wrap the item in foil or remove
the strip and coil it up! A piece of wire about the same length as the
strip (say 16cm) will set off the alarm. A simlpe pocketsized device could
be constructed to demagnetise the device, but if you know how to do that, I
think you got better things to do than shoplift!
Bill
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Path: arc1-ca.pugleaf.net!sparky!uunet!mcsun!sun4nl!ooc.uva.nl!hacktic!bill From: bill@hacktic.nl (Bill Squire) Newsgroups: sci.electronics Subject: Re: How do anti-theft systems in Shops work ??? Keywords: security shops theft Message-ID: <237-PCNews-120beta@hacktic.nl> Date: 15 Apr 92 22:38:02 GMT References: <1613@imec.UUCP> Lines: 12