6 May
2024
6 May
'24
7:15 p.m.
On Mon, May 6, 2024 at 11:59 AM Chuck Guzis via cctalk <
cctalk(a)classiccmp.org> wrote:
On 5/6/24 11:28, Wayne S via cctalk wrote:
At the old Alameda County Computer Resource Center (the non-profit computer
recycler I was shacked up with before I got my own warehouse and started my
own recycling operation), James ("God") designed a bulk demagnetizer that
accommodated several hundred 3.5" floppies at a time. He'd run it for I
think 20 minutes (the period of time he determined was required for 100%
erasure of data), which also had the side effect of heating up the disks,
which had the desirable side effect of making it much easier to peel off
the labels. They sold bulk recycled 3.5" disks and made good money off it
(this is late 1990s).
I wish I could remember the details of how he made it, but he basically
took some existing thing and either modded it in some way or simply
re-purposed it from its intended purpose to conveniently demagnetize floppy
disks.
Sellam
You do need a very strong magnet. I’ve put 3.5
floppies on top of a mag
tape demagnitizer ( not technically called that, but you know what i mean)
and it had no effect at all. I could still read them fine in my pc. I
surmised that the magnetic field generated was not strong enough to get
through the plastic disk shield. Gave up after that.
I made my own PM demagnetizer (I do own a bulk videotape eraser also,
but this one is so convenient and works very well). The trick was to
use two magnets with like poles facing. I got the magnets from a
magnetron--it took a fair amount of clamping to get the things set in
place. Unlike poles facing doesn't work, BTW.
https://i.imgur.com/MUKTExa.jpg
--Chuck
