Alt-BEAM Archive
Message #07225
To: beam@sgiblab.sgi.com
From: "Jim Taylor" ace27@icdc.com
Date: Sun, 31 Oct 1999 17:54:29 -0500
Subject: [alt-beam] Re: Time Capsules
I "smoked" my astro 25 a month or 2 ago. The astro 25 is a BIG motor by
BEAM standards. I run it on 16 ni-cad cells, at 30 amps. One flight topped
50 amps, and the motor siezed up on me. The epoxy coating on the armature
had melted and fused to the magnets! OUCH Anyway the Cobalt magnets were
not effected at all. I also run smaller motors, and from my experience, if
you get a motor hot enough to effect it's magnets strength, you have much
bigger problems then the magnets :)
James Taylor
URL: http://fly.to/springmeadows
7226 Mon, 01 Nov 1999 10:52:14 +1100 [alt-beam] Re: Time Capsules beam "Ben Hitchcock" >From: "Timothy Flytcher"
There's a thing called a 'curie' point in magnets, which is different for
each type of magnet. This was named after the Curies, of course.
This explanation is totally my understanding, and could be wrong. But it's
my best guess.
Basically how it works is that for an atom to have a magnetic charge, the
electrons have to spin around it in a certain direction (either clockwise or
anticlockwise). When a material is unmagnetised, there are equal amounts of
clockwise and anticlockwise spinning electrons. When you magnetise it,
there is a net imbalance - so a net magnetic field.
The curie point is the temperature where the atoms are free to change their
orientation and hence magnetic field. I have done an experiment where a
lump of iron was tested to be magnetic, then heated up, and above the curie
point the material wasn't magnetic.
IF you want to make a strong permanent then hold a permanent magnet next to
a piece of metal as it cools from above its curie point. This makes all
(well, lots, anyway) of the magnetic poles align to the external field,
making a kick-ass magnet. You should use a powerful earth magnet or a
solenoid to make as strong a magnet as possible.
Incidentally this is how geologists can know what the magnetic poles of the
earth have been doing for the past few billion years.
Also, some people when copying magnetic tapes would get out the iron, some
tissues, and go for it. Don't think about copying credit cards this way -
the fields are too weak for it and you will likely heat up the original too
much and lose ITs information!
Ben
>>A magnet does not loose any strenght from age.
>
>Ok Bob... do you know at what temperature they start to degrade???
>
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7227 Sun, 31 Oct 1999 16:25:55 -0800 (PST) [alt-beam] Re: mark tilden beam@sgiblab.sgi.com Evan Dudzik no, he doesnt seem to have enough time to be on it,
too much stuff to do...
7228 Sun, 31 Oct 1999 19:45:41 -0700 Re: Craig's chloroplast SE
> In a message dated 10/31/99 3:49:48 PM Eastern Standard Time,
rigter@cafe.net
> writes:
>
> > Truth is the operating voltage is higher! Nothing else is different with
> > respect
> > to existing SEs!
> >
> Well, it doesn't dump all of it's load. It retains 5 volts that can be
used
> for another purpose. It also is much quicker and efficient and doesn't
need
> to fill the well all the way from the bottom. I would say it is very
> different.
>
> See ya,
> Jim
> http://www.geocities.com/SoHo/Exhibit/8281/beamart.html
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