PSN-L Email List Message
Subject: Re: diamagnetic levitation seismometer possibility
From: Thomas Dick dickthomas01@.............
Date: Wed, 11 Jul 2012 21:44:02 -0500
On 7/11/2012 8:29 PM, chrisatupw@....... wrote:
> Thomas Dick
> To: psnlist
> Sent: Tue, 10 Jul 2012 15:50
> Subject: Re: diamagnetic levitation seismometer possibility
>
> On 7/9/2012 9:34 AM, chrisatupw@....... wrote:
> From: Bob McClure bobmcclure90@.........
>>> I, too, have carried out diamagnetic levitation experiments similar
>>> to those by Meredith Lamb. Although the large amplitude motion looks
>>> smooth and frictionless, what I concluded for very small amplitudes,
>>> such is not the case. The supporting magnetic field has small-scale
>>> roughness, and the levitated graphite tends to hung up in the hills
>>> and valleys of the resulting force.
>>>
>>> I don't understand this. I would only expect 'field roughness' to
>>> show up for linear motions comparable to the levitation height, of
>>> 1/2 to 1 mm, NOT for tiny movements of ~100 nano metres.
>>> One problem that I had with levitating graphite was due to it's
>>> propensity to pick up lint, hairs and dust. These can and do effect
>>> a very light slider. Another problem is the extremely high field
>>> gradients at the edges of the magnets picks up magnetic and
>>> paramagnetic dust only too easily. I clean magnets using a roll of
>>> PVC tape - you stick it onto the surface and then peel it of with
>>> the rubbish attached.
>>> Chris & all ...
>>>
>>> All of you seem locked in on the material being the problem ... and
>>> you may be correct. But what if, the "change" you are "seeing" and
>>> blaming on the field roughness is being induced by earth's magnetic
>>> field or from other radiations from space. I suggest shielding could
>>> be an issue. Some of you might remember a seismic unit I created
>>> years ago using a large horseshoe shaped magnet dampened with oil.
>>> That setup was affected by the 200 watt 10 meter amateur radio
>>> repeater I was operating at the time.
>>>
>>> Hi Tom,
>>> You do have to shield the unit from any air movements VERY
>>> carefully. Also from solar / heat radiation.The 'slider' only
>>> weighs 2 to 3 gm, so it is quite easy to upset it! Strong radio
>>> signals can interfere with the electronics if they are not shielded
>>> well enough. I was using Si photocells, which are fairly resistant
>>> to interference. The magnetic levitation enables the armature to be
>>> suspended freely. It just 'floats in mid air' with 1/2 to 1 mm
>>> clearance over the magnets. I didn't see anything comparable to
>>> Bob's problems.
>>> The principle difficulty is designing / adjusting / trimming the
>>> field 'suspension dish' and the armature to give a usefully long
>>> period. From memory, the longest period that I got was about 8
>>> seconds. This would still require a specialist VLF boost amplifier
>>> to get periods of out to about 20 seconds. It might be more
>>> practical to choose a period of 3~4 seconds, which is much easier to
>>> attain.
>>> Regards,
>>> Chris
Chris, I am not in these guys' league. I did fool around with floating
magnets and light sensor over ten years ago when I first started. I
finally did get a large horseshoe magnet (actually hung as a pendulum)
to produce good results at about 2 Hz on the horizontal plane and not
the vertical as I had hoped, But I had to use a very strong magnetic
field and oil dampening around it --- and wire mess, too, just to keep
what I call sporatics out. This provided a useable /*amateur*/ unit. I
learned a lot from these two adventures. Even with the best shielding
there is risk of contamination. Plus, now, astronomers and physicists
are talking of particles capable of passing right through the earth
itself. Maybe ignoring the sunspot activity which is so sporadic isn't a
good idea either. I think the electronics we use today is good but I am
not confident that the "effects" are as easily explained. We may be
seeing the result of something entirely different than material
impurities can explain. Did you know that they are suggesting that
space is a web and not a vacuum?
I, too,
have carried
out
diamagnetic
levitation
experiments
similar to
those by
Meredith Lamb.
Although the
large
amplitude
motion looks
smooth and
frictionless,
what I
concluded for
very small
amplitudes,
such is not
the case. The
supporting
magnetic field
has
small-scale
roughness, and
the levitated
graphite tends
to hung up in
the hills and
valleys of the
resulting
force.
I
don't
understand
this. I would
only expect
'field
roughness' to
show up for
linear motions
comparable to
the levitation
height, of 1/2
to 1 mm, NOT
for tiny
movements of
~100 nano
metres.
One problem
that I had
with
levitating
graphite was
due to it's
propensity to
pick up lint,
hairs and
dust. These
can and do
effect a very
light
slider. Another
problem is the
extremely high
field
gradients at
the edges of
the magnets
picks up
magnetic and
paramagnetic
dust only too
easily. I
clean magnets
using a roll
of PVC tape -
you stick it
onto the
surface and
then peel it
of with the
rubbish
attached.
Chris &
all ...
All of you seem
locked in on the
material being
the problem ...
and you may be
correct. But
what if, the
"change" you are
"seeing" and
blaming on the
field roughness
is being induced
by earth's
magnetic field
or from other
radiations from
space. I suggest
shielding could
be an issue.
Some of you
might remember a
seismic unit I
created years
ago using a
large horseshoe
shaped magnet
dampened with
oil. That setup
was affected by
the 200 watt 10
meter amateur
radio repeater I
was operating at
the time.
Hi
Tom,
You do have to
shield the
unit from any
air movements
VERY
carefully.
Also from
solar / heat
radiation.The 'slider'
only weighs 2
to 3 gm, so it
is quite easy
to upset it!
Strong radio
signals can
interfere with
the
electronics if
they are not
shielded well
enough. I was
using Si
photocells,
which are
fairly
resistant to
interference.
The magnetic
levitation
enables the
armature to be
suspended
freely. It
just 'floats
in mid air'
with 1/2 to 1
mm clearance
over the
magnets. I
didn't see
anything
comparable to
Bob's
problems.
The principle
difficulty is
designing /
adjusting /
trimming the
field
'suspension
dish' and the
armature to
give a
usefully long
period. From
memory, the
longest period
that I got was
about 8
seconds. This
would still
require a
specialist VLF
boost
amplifier to
get periods of
out to about
20 seconds. It
might be more
practical to
choose a
period of 3~4
seconds, which
is much easier
to attain.
Regards,
Chris
Chris, I am not in these guys' league. I did fool around with
floating magnets and light sensor over ten years ago when I first
started. I finally did get a large horseshoe magnet (actually hung
as a pendulum) to produce good results at about 2 Hz on the
horizontal plane and not the vertical as I had hoped, But I had to
use a very strong magnetic field and oil dampening around it --- and
wire mess, too, just to keep what I call sporatics out. This
provided a useable amateur unit. I learned a lot from
these two adventures. Even with the best shielding there is risk of
contamination. Plus, now, astronomers and physicists are talking of
particles capable of passing right through the earth itself. Maybe
ignoring the sunspot activity which is so sporadic isn't a good idea
either. I think the electronics we use today is good but I am not
confident that the "effects" are as easily explained. We may be
seeing the result of something entirely different than material
impurities can explain. Did you know that they are suggesting that
space is a web and not a vacuum?
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