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From: wn9nbt@pur-ee.UUCP (Dave Chasey)
Newsgroups: sci.electronics
Subject: Re: Stolen item-detectors (Was: Re: Laser eavesdropping)
Message-ID: <5941@pur-ee.UUCP>
Date: Mon, 13-Apr-87 10:57:15 EST
Article-I.D.: pur-ee.5941
Posted: Mon Apr 13 10:57:15 1987
Date-Received: Sat, 18-Apr-87 23:38:48 EST
References: <959@obelix.UUCP> <1104@nonvon.UUCP>
Reply-To: wn9nbt@pur-ee.UUCP (Dave Chasey)
Organization: Electrical Engineering Department , Purdue University
Lines: 13


I have always wondered about these alarms also.   The ones mentioned
here seem to involve clips that are removed, or the ones that the
ones that are destroyed when you pay for the item.  How about the
ones that are in Library books in some libraries ?  They are
able to activate the sensor when the book is on the shelf and deactivate
it when you check the book out.   In our engineering library, I saw
a student check out a few books, but they forgot to deactivate
one of the books.   The alarm went off as the student left, so he returned
and they found the book and deactivated the sensor and he went thru
with no problem.    I have been told that the sensor is on the back
side of the envelope that they attach inside the rear cover that holds
the checkout card.   Any ideas ??............Dave