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From: wdp@ee.egr.duke.edu (William D. Palmer)
Newsgroups: sci.electronics
Subject: Re: Library anti-theft walk-thru device...????
Summary: One-way detection
Message-ID: <1425@cameron.egr.duke.edu>
Date: 9 May 91 02:51:11 GMT
References: <050691.224256WDBURNS%MTUS5.BITNET> <91127.230228ART100@psuvm.psu.edu>
Sender: news@egr.duke.edu
Lines: 23

In reference to your posting:

> From: ART100@psuvm.psu.edu (Andy Tefft)
> Date: 8 May 91 03:02:28 GMT

> I have a friend who uses an electric wheelchair ...

(Stuff about theft detection device deleted.)

> Why would this be?

Try getting him to go out backwards.  If that gives you the same response
as coming in, there's some non-symmetry in the magnetic metal parts on the
chair that's disturbing the theft detection device.

Dev Palmer
wdp@dukee.egr.duke.edu
Duke Electrical Engineering
Room 309 Old Engineering Bldg.
Durham, NC  27706
(919) 660-5282

"I'm from North Carolina and I DON'T support Jesse Helms!"