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:
And if you wish a quick refresher on magnetic units, please see
I hope that helps.
At 04:32 PM 2008-08-26, you wrote:
>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?
>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.