Jim Scholtz (
Tue, 12 Aug 1997 11:49:00 -0600 (MDT)

Hi Tom,
We have the Knogo magnetic system installed at our library (Yankton, SD).
It is analogous to 3M tattle/whispertape (3M bought out Knogo last year).
We have not had any problems with CDs (music or otherwise) going through
the security gates or being desensitized/sensitized. The CD has physical
indentations and does not use a magnetic recording playback system at
all, so it would not be affected by electromagnetic desensitization.
The checkpoint system uses foil reflecting radio waves and would not
affect the playback of a CD. However, the foil embedded in the plastic
of CDs can make the security gates go off if the angle of deflection is
just right.
Jim Scholtz, Yankton Community Library, Yankton, SD.
On Mon, 11 Aug 1997, Audio-Visual Department wrote:

> We had a librarian ask us if the circulation sensitizer/de-sensitizer
> affects a cd-rom if it is scanned across. Thanks in advance.
> Tom Finnigan
> Mid-Hudson Library System