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-boun...@classiccmp.org> on behalf of Tapley, Mark via cctalk <cctalk@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@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