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Hello, Jonathan,

To keep things in perspective, most motors and other devices that use 
electromagnetism keep most of it inside in order to improve efficiency.

If I recall correctly, the DC magnetism of the earth is 0.5 Gauss.

The best reference I'm aware of is here:
http://home.flash.net/~mrltapes/field-strength-for-partial-erasure.pdf

And if you wish a quick refresher on magnetic units, please see
http://www.irm.umn.edu/hg2m/hg2m_a/hg2m_a.html

I hope that helps.

Cheers,

Richard


At 04:32 PM 2008-08-26, you wrote:
>Hi all,
>
>We have most of our audio collections housed in powered mobile storage
>units (Spacesaver Eclipse EC300). A colleague from another institution
>recently mentioned that they had chosen manual mobile storage due to the
>potential interference from the motor on magnetic-based audiotape. The
>EC300 uses a 90VDC motor, 1/6HP, 5 amp max, 120VAC 60Hz. There is
>approx. 3-4" between the motor and the lowest storage shelf. Is that
>enough to cause interference with the audio signal?
>
>Many thanks,
>Jonathan
>
>Jonathan Wise
>Audiovisual Archives
>Canadian Museum of Civilization

Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.