17 Jun
2002
17 Jun
'02
9:32 a.m.
I just found a box of stuff that hasn't seen the light of day since my
company moved to our current building some 15 years ago.
In it was a Bulk Tape Eraser. The box pictures it being used on 5.25
floppies (as well as an 8 track tape and reel to reel tape). Is it safe
to use on floppy disks? I have a stack of HD 3.5's that I want to blank
out. Previously I just run them thru a computer to format them, but if a
bulk tape eraser can be used, it just saves me the trouble.
Also, how exactly are you supposed to use one? It has been as long since
I used one (probably this same one, used to use it to blank reel to reel
audio tapes). I thought I remembered that all you do is turn it on, hold
it over the item for a few seconds, wave it back and forth a bit, and
that was it. The item would be erased.
I just tried this one on a VHS video tape, it doesn't seem to do anything
to it. The picture is slightly distorted, but the tape is certainly not
blanked, not even close. I left it on for a good 30 to 45 seconds (the
label on the side of it says 1 minute on 20 minutes off, so I didn't want
to go beyond 1 minute).
It has a momentary switch on the handle, so it clearly isn't designed to
be left on very long. It makes a slight humm when on (and vibrates just a
touch, nothing visible, but you can feel it in your hand) so I assume it
is working. However, this is a Radio Shack brand item, so who knows if it
is doing what it should considering it is probably over 20 years old.
Any clues?
-chris
<http://www.mythtech.net>
17 Jun
17 Jun
10:44 a.m.
Chris wrote:
I just found a box of stuff that hasn't seen the light of day since my
company moved to our current building some 15 years ago.
In it was a Bulk Tape Eraser. The box pictures it being used on 5.25
floppies (as well as an 8 track tape and reel to reel tape). Is it safe
to use on floppy disks? I have a stack of HD 3.5's that I want to blank
out. Previously I just run them thru a computer to format them, but if a
bulk tape eraser can be used, it just saves me the trouble.
Also, how exactly are you supposed to use one? It has been as long since
I used one (probably this same one, used to use it to blank reel to reel
audio tapes). I thought I remembered that all you do is turn it on, hold
it over the item for a few seconds, wave it back and forth a bit, and
that was it. The item would be erased.
I just tried this one on a VHS video tape, it doesn't seem to do anything
to it. The picture is slightly distorted, but the tape is certainly not
blanked, not even close. I left it on for a good 30 to 45 seconds (the
label on the side of it says 1 minute on 20 minutes off, so I didn't want
to go beyond 1 minute).
It has a momentary switch on the handle, so it clearly isn't designed to
be left on very long. It makes a slight humm when on (and vibrates just a
touch, nothing visible, but you can feel it in your hand) so I assume it
is working. However, this is a Radio Shack brand item, so who knows if it
is doing what it should considering it is probably over 20 years old.
Any clues?
yeah, they work great on floppies, even on some with soft errrors that
formatting doesn't remove. Just keep in mind you'll still have to
format the floppy after the degaussing.
Wasn't suprised to see that it doesn't do VHS tapes very well. You need
quite a bit more gauss to do those, but a hand held will do floppies,
cassettes and 1/4" tape pretty well.
To use, squeeze the trigger switch while the demagger is away from the
media, and bring it up and slide it over and around in a random pattern
for several seconds, 10-30 seconds is usually adequate, then remove the
media while holding on to the switch. This eliminates a big glitch of
magnetism on the media.
What ever you do, DO NOT USE a degausser on a hard drive. There is
embedded information on the tracks for tracking, and if removed, you
need a high cost formatter. Bottom line . . . demag a HD and it becomes
a doorstop.
Gary Hildebrand
St. Joseph, MO
11:02 a.m.
I left it on for a good 30 to 45 seconds (the label on
the side of it says 1 minute on 20 minutes off, so I didn't...
The time I remember seeing one used:
Move it like an iron, back and forth, back and forth.
In general, moving magnetic fields are more
influential than stationary ones.
John A.
18 Jun
18 Jun
1:11 a.m.
At 07:02 PM 6/17/02 -0400, you wrote:
Wouldn't switching it on and off be many times more
efficient at producing a time-varying field? :-) .
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
I left it on
for a good 30 to 45 seconds (the label on
the side of it says 1 minute on 20 minutes off, so I didn't...
The time I remember seeing one used:
Move it like an iron, back and forth, back and forth.
In general, moving magnetic fields are more
influential than stationary ones.
John A. 
10:26 a.m.
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3:23 p.m.
At 11:26 PM 6/18/02 +0100, you wrote:
It shows that I haven't been near one of them. But I did
repair the "eraser" for magnetic strips embedded in the
spine of all books at one of the Cornell University libraries,
where I worked for a while. Method: charge a few big caps
to about 340V, then discharge suddenly through a big coil.
Dangerous.
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
Wouldn't
switching it on and off be many times more
efficient at producing a time-varying field? :-) .
Isn't that one reason that those erasers run on AC?
-tony 
19 Jun
19 Jun
1:45 a.m.
Hmm... All this talk of erasing things has got me thinking... If I need to
erase some tapes, do you think taking them near one of the NMR magnets here
and waving them around would do the trick?
Carlos Murillo said:
At 11:26 PM 6/18/02 +0100, you wrote:
It shows that I haven't been near one of them. But I did
repair the "eraser" for magnetic strips embedded in the
spine of all books at one of the Cornell University libraries,
where I worked for a while. Method: charge a few big caps
to about 340V, then discharge suddenly through a big coil.
Dangerous.
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
- Dan Wright
(dtwright(a)uiuc.edu)
(http://www.uiuc.edu/~dtwright)
-] ------------------------------ [-] -------------------------------- [-
``Weave a circle round him thrice, / And close your eyes with holy dread,
For he on honeydew hath fed, / and drunk the milk of Paradise.''
Samuel Taylor Coleridge, Kubla Khan
Wouldn't switching it on and off be many times more
efficient at producing a time-varying field? :-) .
Isn't that one reason that those erasers run on AC?
-tony 
20 Jun
20 Jun
3:52 a.m.
On Tue, Jun 18, 2002 at 11:26:45PM +0100, Tony Duell wrote:
AC makes a field that alternates its direction with
constant peeks.
Moving the degauser away while it is running makes a field with
degreasing peeks. This is needed to actually degaus the media.
Switching the degauser off when it is near the media leaves the
media in a gaused state, possibly gaused in a way that a drive
gets confused or can't reformat the media. You need the alternating
and degreasing field to bring the hysteresis down to zero. If you
think of a magnetic hysteresis curve, you need a field that produces
a hysteresis curve that looks like a spiral. I.e. alternating with
degreasing amplitude. You can see this well when a monitor is
degaused.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
Wouldn't
switching it on and off be many times more
efficient at producing a time-varying field? :-) .
Isn't that one reason that
those erasers run on AC?
17 Jun
17 Jun
11:50 a.m.
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4:37 p.m.
On Mon, 17 Jun 2002, Chris wrote:
I just found a box of stuff that hasn't seen the
light of day since my
company moved to our current building some 15 years ago.
In it was a Bulk Tape Eraser. The box pictures it being used on 5.25
floppies (as well as an 8 track tape and reel to reel tape). Is it safe
to use on floppy disks? I have a stack of HD 3.5's that I want to blank
Yep, the only time it is unsafe is when you discover that the one you
degaussed had valuable data on it :)
out. Previously I just run them thru a computer to
format them, but if a
bulk tape eraser can be used, it just saves me the trouble.
Also, how exactly are you supposed to use one? It has been as long since
I used one (probably this same one, used to use it to blank reel to reel
audio tapes). I thought I remembered that all you do is turn it on, hold
it over the item for a few seconds, wave it back and forth a bit, and
that was it. The item would be erased.
The usual technique on disks is to hold the eraser on the disk, make a
few spiral `circles' on it and then draw the eraser about two feet away
before cutting power. Because of the steel hub, 3.5" disks make a bit
of racket when you work on them, but the only thing it hurts is your
ears!
I just tried this one on a VHS video tape, it
doesn't seem to do anything
to it. The picture is slightly distorted, but the tape is certainly not
blanked, not even close. I left it on for a good 30 to 45 seconds (the
label on the side of it says 1 minute on 20 minutes off, so I didn't want
to go beyond 1 minute).
That is a fairly conservative limitation. Perhaps valid if in a
production mode and total time is significant.
It has a momentary switch on the handle, so it clearly
isn't designed to
be left on very long. It makes a slight humm when on (and vibrates just a
touch, nothing visible, but you can feel it in your hand) so I assume it
is working. However, this is a Radio Shack brand item, so who knows if it
is doing what it should considering it is probably over 20 years old.
Yes, I have a couple of them - one larger than the other. Also, a
tabletop model that is intended for 0.25" tape reels on home recorders.
Used to use that to degauss 5.25" floppies.
- don
Any clues?
-chris
<http://www.mythtech.net>
8267
days inactive
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9 comments
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participants (8)
-
allain＠panix.com -
ard＠p850ug1.demon.co.uk -
carlos_murillo＠epm.net.co -
donm＠cts.com -
dtwright＠uiuc.edu -
ghldbrd＠ccp.com -
jkunz＠unixag-kl.fh-kl.de -
mythtech＠mac.com