It takes alot more power to erase DV tapes than what
Hand Held Radio Shack Bulk Tape Erasers can handle.
Here's a chart showing the power needed to erase DV Tapes.
(It takes 1700 Oersteds to erase DV tapes.)
Coercivity is the property of a given magnetic pigment to resist changes in magnetic orientation or re-orientation (= "erasure"). It is defined by the level of the magnetic field needed for (re-)orientation, expressed in Oersted (Oe). The higher the coercivity, the higher the resistance of magnetic information to re-orientation (or erasure) by external magnetic fields.
AUDIO Tapes Oersteds
==================================
350 Oersteds = 1/2", 1" and 2"
350 Oersteds = Cartridge
350 Oersteds = Sep.mag.35mm film
365 Oersteds = Voice logging reel 1/2", 1"
450 Oersteds = Compact cassette ferric (IEC Type I)
450 Oersteds = Compact cassette chrome (IEC Type II)
680 Oersteds = 1/4", 1/2" digital audio reel
745 Oersteds = 3/4" digital audio cassette
10/750 Oersteds = Pancake various
700 Oersteds = DCC
930 Oersteds = ADAT
1440 Oersteds = RDAT
COMPUTER/Data Tapes Oersteds
==================================
300/700/1500 Oersteds = Floppy diskette 51/4",31/2"
550 Oersteds = PC,Mini, Hard disk
310 Oersteds = Main-frame Spool 1/2"
550/650 Oersteds = Cartridge
1500 Oersteds = TK50 etc.
700 Oersteds = DCRSI cassette
310 Oersteds = Reel 1/2", 1"
675/750 Oersteds = Cassette
1050/1500 Oersteds = 8mm/4mm
1440 Oersteds = DAT-R
550 Oersteds = Cartridge 3480, DC600A
1900 Oersteds = Digital backup cartridge
VIDEO Tapes Oersteds
==================================
750 Oersteds = Reel 1"`B'and`C' format
300 Oersteds = 2"
675/750 Oersteds = VHS pancake
2100 Oersteds = Mirror master
675/700 Oersteds = Cassette VHS
710 Oersteds = Beta
1000 Oersteds = SVHS
1050/1500 Oersteds = Hi8
630 Oersteds = U-matic
745 Oersteds = U-matic SP
1700 Oersteds = Beta SP, MII
850 Oersteds = D-1
1700 Oersteds = D-2, D-3 Digital
1700 Oersteds = Digital Betacam, D5 Digital
1700 Oersteds = DV, DVC, DVCAM, DVC PRO
SECURITY formats Oersteds
==================================
600 Oersteds = Credit card
600 Oersteds = Library ticket
600/3500 Oersteds = Rail/Air ticket
600 Oersteds = Hotel door lock
(INFO FROM: <a href="http://www.weircliffe.co.uk/degaussi.htm">Weircliffe</a>)
Here's something interesting:
==============================
From: Art Munson <artmuns@tape.com>
Subject: Degaussing, erasing and magnetism
Date: Tue, 27 Aug 1996 11:58:42 -0500 (CDT)
Degaussing, Erasing and Magnetism
---------------------------------
A lot of folks have asked about degaussing (erasing) media and
particularly DAT tapes, so here's some info you might find helpful.
Gauss: A unit of measurement of magnetic flux density produced by a
magnetic force (coils). Gauss is a measurement of coil strength.
Oersted: A unit of magnetic intensity of a magnetic field in a vacuum.
Oersted is a measurement applied to media. A 4mm DAT tape
has a magnetic field strength of approximately 1500 oersteds.
Coercivity: The amount of applied magnetic field (of opposite polarity)
required to reduce magnetic induction to zero. The ease or
difficulty by which magnetic media can be de-magnetized.
A 4mm DAT tape is a high coercivity tape.
So:
1.) The higher the oersted rating, the more energy needed to *properly*
demagnetize it.
2.) In order to degauss (erase) a magnetic tape, a magnetic force (gauss)
of 2 2/3 to 5 times greater than that of the media to be degaussed
must be created. In other words to demagnetize a media of a given
oersted rating, it will take 2 2/3 to 5 times the amount of energy.
3.) A 1500 oersted tape would need a magnetic field strength in the
neighborhood of at least 3000 gauss in order to *properly* erase it.
Hope this helps and thanks to David Partridge for his input.
There is a hand held DAT degausser available, with an oersted rating of
2800, that lists for $169. Please give a call at 800-321-5738 if you are
interested.
Art
* Cassette House
* e-mail:artmuns@tape.com
* DAT tape - CDR's - Cassettes
* web page http://www.tape.com/ch
* 800-321-5738 "I will use no track before its time"
(INFO FROM: <a href="http://www.solorb.com/dat-heads/digests/V2.900/D921">DAT Digest</a>)
==================================
Radio Shack's High Power Gauss Field is 800 oersteds.
<a href="http://support.radioshack.com/support_video/doc14/14741.htm">Specs</a>
==================================
So as you can see, degaussing DV tapes can be done with the
right equipment. Let's see...to erase a DV tape of
1700 Oersteds I need a degausser that can handle 3400 Oersteds.
Hmmm, The Radio Shack High Power Bulk Tape Eraser handles 800 Oersteds.
No wonder it didn't work.