🚀 go-pugleaf

From article <1993Jan1.234107.1@vms.ucc.okstate.edu>, by v923137@vms.ucc.okstate.edu:
> In article <1hsqkaINNlrs@agate.berkeley.edu>, andywang@crown.berkeley.edu (Andrew Wang) writes:
>> .....
>> I took a bunch of old 360k floppies and put them in the middle of
>> a 12" monitor degaussing coil. After 10 seconds of degaussing, I tried
>> three of the diskettes and could still read their directories no problem.
>> .....
> 
> I have successfully erased beyond recognition 5 1/4" and 3 1/2" disks using
> a 40oz. magnet from the back of a 12" woofer, so it is possible....

A monitor degaussing coil is designed to demagnetize materials that
were not designed to retain magnetism and were accidentally magnetized.

The coating on a floppy disk is designed to be magnetized by a write
head that is practically touching it, and to hold that magnetism until
the same or another head, also practically touching it, does something
equally drastic.  It has abrupt magnetic hysteresis: that is, nothing
affects it until the magnetic field you apply to it is just strong
enough, and then it reverses its magnetic polarity.  A disk drive is
built to apply the necessary fields to that material.

I'm not surprised that a monitor degaussing coil could not affect a
floppy, or that a 40 oz. woofer magnet rubbed against it could.

							Marty
marty@hoqaa.att.com		hoqaa!marty
Martin B. Brilliant		(Winnertech Corporation)