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Bulk erase methods

B

Barry Lennox

Jan 1, 1970
0
Hi


What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?

Old magnetron magnets will do the job very nicely.

Barry Lennox
 
Hi


What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?


NT
 
M

Michael A. Terrell

Jan 1, 1970
0
Hi

What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?

NT

There is no magnetic field in a microwave oven, just microwaves.
--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida
 
G

Guy Macon

Jan 1, 1970
0
What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?

Radio shack VHS tape demagnetizer. Cheap and effective.
 
Hi


What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?


NT

If you have a burned out large diameter "woofer", disassemble it to get
to the magnet structure. You can leave the iron pieces attached, just remove
the cone and its support "basket". After you degauss your floppies, you can use
it as the worlds strongest refrigerator magnet.

Jim
 
K

Ken Smith

Jan 1, 1970
0
Michael A. Terrell said:
There is no magnetic field in a microwave oven, just microwaves.

There is indeed a magnetic field. It just isn't good as a bulk eraser.
Get a compass and see.
 
On 11 Jul 2005 15:45:50 -0700, [email protected] wroth:
If you have a burned out large diameter "woofer", disassemble it to get
to the magnet structure. You can leave the iron pieces attached, just remove
the cone and its support "basket". After you degauss your floppies, you can use
it as the worlds strongest refrigerator magnet.

Jim

thanks, will try that.

NT
 
C

colin

Jan 1, 1970
0
Hi


What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

Cant think of anything else that causes a strong enough mag field...
any ideas?

you could heat them up to above their curie point,
u forgot to mention if you wanted to use them again afterwards ?

u could always just use the magnet off the magnetron.

Colin =^.^=
 
G

Guy Macon

Jan 1, 1970
0
Barry said:
Old magnetron magnets will do the job very nicely.

Magnets do indeed destroy data, but if that's all he wants to do
a bonfire is even better. If he wants to re-use the floppies he
would be better off with something that creates an alternating
magnetic field.
 
J

Jeff

Jan 1, 1970
0
If you have a burned out large diameter "woofer", disassemble it to get
to the magnet structure. You can leave the iron pieces attached, just remove
the cone and its support "basket". After you degauss your floppies, you can use
it as the worlds strongest refrigerator magnet.

Jim

I thought that's what those small rare earth neo hard drive magnets are for!
I've have seen people dent fridges trying to get those off.

As long as the flux concentrating steel rings/disk are still there on large
speaker magnets, they can have an impressive flux field in the circular gap.
 
I thought that's what those small rare earth neo hard drive magnets are for!
I've have seen people dent fridges trying to get those off.

Ah yes... could you remind me which part of the HDD they are used in? I
have a dead one to hand...

cheers, NT
 
What methods can be used to bulk erase a lot of floppies? I dont have
one of those nice big electromagnets, and was wondering if anything
else to hand could be used. I presume 2 seconds in a microwave with a
load to prevent sparking is too risky, though I should try one.

might sitting the flop on a piece of metal foil result in enough
magentism? In an oven with a load to prevent arcing. I'll try it
anyway, and let you know how many floppy drive heads I trashed.

NT
 
N

Naveed

Jan 1, 1970
0
Guy Macon said:
Magnets do indeed destroy data, but if that's all he wants to do
a bonfire is even better. If he wants to re-use the floppies he
would be better off with something that creates an alternating
magnetic field.

If the magnet was attached to a drill running at low speed then that would
cause an alternating magnetic field.

Naveed
 
B

Ben Bradley

Jan 1, 1970
0
Ah yes... could you remind me which part of the HDD they are used in? I
have a dead one to hand...

The really strong ones surround the coils that move the head arm.
 
G

Guy Macon

Jan 1, 1970
0
Naveed said:
If the magnet was attached to a drill running at low speed then that would
cause an alternating magnetic field.

Excellent point.

Which brings up the question, what is the optimal frequency?
With an electromagnet you get 50/60 Hz unless you go to a lot
of effort to get another frequency - and it works well - but
with a motor/magnet it's easy to pick a frequency.
 
R

Rich Grise

Jan 1, 1970
0
Excellent point.

Which brings up the question, what is the optimal frequency?
With an electromagnet you get 50/60 Hz unless you go to a lot
of effort to get another frequency - and it works well - but
with a motor/magnet it's easy to pick a frequency.

The frequency is irrelevant. The point is to have a strong enough
magnetic field to line up all of the little magnetic thingies in
the media, and then turn them all around on the next half-cycle.

A permanent magnet will line up all the little thingies, but then
you've got a magnet bias that could introduce confounding factors
when re-using the media.

Anyway, with the AC field (hey, there's a usage of AC that we
didn't consider in the "Tastes Great-Less Filling" ACDC thing!),
just twirl the magnet fast enough that it can sweep the field
over the media once or twice.

Then, the secret is, slowly move the moving magnet ( or half
a transformer, or whatever) away from the media, and as the
alternating field gets weaker and weaker, reversing fewer
and fewer thingies, until on the average, there's no
residual magnetism in the media.

It's the same principle with CRT degaussers, but they use
a PTC thermistor in series with the coil. Press the degausser
button on your monitor - see the pretty patterns? And how
they decay? That's the principle that ends up with
negligible residual magnetization. I know there's a whole
nother jargon here, but, come on! :)

Anyway, Hope This Helps!

Cheers!
Rich
 
M

Michael A. Terrell

Jan 1, 1970
0
Guy said:
Excellent point.

Which brings up the question, what is the optimal frequency?
With an electromagnet you get 50/60 Hz unless you go to a lot
of effort to get another frequency - and it works well - but
with a motor/magnet it's easy to pick a frequency.


It has to be a low frequency to penetrate the magnetic layer. Also
the magnet would have to be mounted so the north and south poles would
alternate. A magnet from a speaker would have to be mounted from its
edge to work.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
Ken said:
There is indeed a magnetic field. It just isn't good as a bulk eraser.
Get a compass and see.


A magnetic field inside the oven? The metal might have a small
residual field, but you need a changing magnetic field to degauss the
magnetic media.

BTW: a compass will point to any piece of steel that is large enough,
and close enough.

--
Link to my "Computers for disabled Veterans" project website deleted
after threats were telephoned to my church.

Michael A. Terrell
Central Florida
 
K

Ken Smith

Jan 1, 1970
0
A magnetic field inside the oven? The metal might have a small
residual field,

(Go back and read what I replied to. The prev. post said there was no
magnetic field inside a microwave oven)

I don't have advanced equipment here but lets assume that the earths
field is about 0.5G in the middle of my kitchen. Outdoors within 20 miles
of here, it is 0.495G or so, so I think this is accurate enough what I'm
about to do.

I hold the compass in the middle of the kitchen and note the direction of
the pointer.

Next I bring a small magnet towards the compass from what it indicates is
the east while rotating the magnet to find the orientation that causes the
greatest deflection.

When I obtain a 45 degree deflection, the magnet is making as much field
at the compass as the horz. component of the earths field. I measure this
distance and find it to be just about 4.25 inches.

We know that where I am the earths field is just about 0.5G and dipped by
about 60 degrees. This means that the magnet at 4.25 inches is producing
a field of:

0.5G * cos(60) = 0.25G

Next I place the compass inside a Panasonic microwave on a non-magnetic
book such that the compass is about 1.5 inches above the bottom of the
oven, and nearly centered. Again I observe the compass pointer and
introduce the magnet from its east until I obtain a 45 degree deflection.
I measure this distance. I comes out to be just about 2 inches.

The magnet I'm using is 0.25 inches in its largest direction so I feel
safe in using the small dipole estimate. Therefor I calculate the horz
component of the field inside the oven is:


0.25G * (4.25/2)^3 = 2.4G

Since this is the Horz component it represents a minimum for the field
value. It is a lot more than "no magnetic field" but as I pointed out not
one that will be good as a bulk eraser.

but you need a changing magnetic field to degauss the
magnetic media.

Actually you don't need a changing field if you are allowed to change the
location of the magnetic media, but that is too much of a quibble.
 
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