Re: iPad 2 cover vs. Floppy disks

["Michael J. Mahon" <mjmahon@aol.com>]

Linards Ticmanis wrote:
> On 04/30/2011 08:19 AM, Michael J. Mahon wrote:
>
>
> > Actually, you can always degauss a CRT whose shadow mask
> > has become magnetized, though you may need to improvise
> > a degaussing coil these days.  ;-)
>
>
> What do you use for that? I was under the impression that you need a big
> coil and a fuse-busting amount of Amperes to create a useful field.

A large degaussing coil (around 14") will require a few amps--but
for less than a minute.  Smaller coils, like bulk tape erasers, will
use only one or two amps, and are quite adequate for Apple monitors.

I used to use a Wen soldering gun, and the one-turn coil containing
the soldering tip generated a strong AC field that could be used for
degaussing.  Weller guns also work, but mine had a weaker field.

In all cases, degaussing involves subjecting the magnetized material
to a field stronger than its coercivity, then slowly decreasing the
field (by backing away) until the remanent field in the material is
essentially zero.

If the degaussing field is stopped suddenly, it will leave materials
*magnetized* instead of demagnetizing them, so be sure to follow the
instructions for demagnetizing!

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

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