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Path: utzoo!mnetor!seismo!columbia!rutgers!andromeda!argus!ken
From: ken@argus.UUCP (Kenneth Ng)
Newsgroups: sci.electronics
Subject: Re: Library Book detectors
Message-ID: <849@argus.UUCP>
Date: Thu, 30-Apr-87 06:03:28 EDT
Article-I.D.: argus.849
Posted: Thu Apr 30 06:03:28 1987
Date-Received: Sat, 2-May-87 07:51:36 EDT
References: <146@illusion.UUCP> <868@oliveb.UUCP> <1726@kitty.UUCP> <1640@nicmad.UUCP>
Organization: NJ Instit. of Tech: TEIES Project
Lines: 31

In article <1640@nicmad.UUCP>, kunert@nicmad.UUCP (Dick Kunert) writes:
> In article <1726@kitty.UUCP>, larry@kitty.UUCP (Larry Lippman) writes:
> > 	Now, THINK, people!  How does this system work???  It's really
> > rather clever!  If no one guesses the correct answer, I'll post it in a
> > week.
> I worked in a library that used a similar system, but there was no way
> to deactivate the sensor. The "tag" inserted in the book was just a
> printed loop connected to a printed capacitor forming a resonant circuit-
> the system was designed so that the library employee would pass the books
> around the sensor at the checkout.

At least one system works magnetically.  Before the remodeling the local
college library had a device it passed books through before giving them
back to you.  I balanced my trusty 6 inch steel ruler on a finger.
When the book went through the ruler went flying and inpinged against
the device.  Unfortunately the new system is moved out of range, so I
can't test it.  Maybe my Cheshire cat grin gave them the hint that I
figured out at least part of the system.

>                       ihnp4-\                  "I'm looking for a lifestyle
> Dick Kunert      seismo!uwvax!nicmad!kunert     that doesn't require my
>                      decvax-/                   presence..." 

-- 
Kenneth Ng: Post office: NJIT - CCCC, Newark New Jersey  07102
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