16 Mar
2017
16 Mar
'17
8:06 p.m.
That is in fact how I spot degauss CRT screens, but using a flat wood
boring bit (metal, obviously, instead of a paint stick) with the magnet
stuck on the end, spun around with a drill.
- J.
On 3/16/2017 6:37 PM, dwight via cctalk wrote:
It sounds like one can make a fine tape degausser by
connecting
a super magnet to the end of a paint stirring rod and use a drill
to spin it.
Dwight
________________________________
From: cctalk<cctalk-bounces at classiccmp.org> on behalf of Tapley, Mark via
cctalk<cctalk at classiccmp.org>
Sent: Wednesday, March 15, 2017 11:51:07 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: AC magnetic field strengths
On Mar 15, 2017, at 12:01 PM, Al Kossow via cctalk<cctalk at classiccmp.org>
wrote:
I bought an AlphaLabs GM-2 Gaussmeter for another
project, and measured the AC magnetic
field strength touching these devices yesterday, since I really didn't have any idea
beyond
order of magnitude what they might be
Handheld tape head demagnetizer: 40 Gauss
GC Elec 9317 CRT degausing coil: 70 Gauss
Audiolab TD-3 desktop bulk eraser: 1000 Gauss
Inmac 7180 or
RS 44-233A handheld bulk tape erasers: 2000 Gauss
also the DC field of a 1/4" button super magnet like on the
backs of clip on badges is about 3000 Gauss
More context available at:
https://en.wikipedia.org/wiki/Orders_of_magnitude_(magnetic_field)
ranging from 50 femtoGauss (what the Gravity Probe B SQUID magnetometers measured with
several days? averaging) to 100 MegaGauss (strongest pulsed field ever obtained at Sandia
Labs).
Interestingly that page claims 12.5 kGauss for a "neodymium?iron?boron (Nd2 Fe14 B)
rare earth magnet? (subscripts on the atomic symbols got converted to plain text during
cut-n-paste). Guess the badges have weaker versions?
Interesting to compare earth field and the badge fastener field to practical exposure
limit for pacemakers - only about a factor of 10 at the poles - and to loudspeaker coils,
which are 5000 times above the recommended pacemaker limit.
Now I know why people with pacemakers don?t like rock music (and name tags)!
:-)
- Mark