Subject: (Tegenfeldt) Cars Rotating static field (fwd)
Date: Fri, 11 Jun 1999 143227 -0500 (CDT)
From: "Roy L. Beavers" <rbeavers@llion.org>
To: emfguru <rbeavers@llion.org>
--------------------------------------------------
.......Good to hear from Clas again!!..... As usual his contribution
(below) is very worth while......
After you have read it, try to think about people (men) you know who have
worked for many years "on the road".... Prostate problems???.....
Roy Beavers (EMFguru)......
rbeavers@llion.org.......
.....It is better to light a single candle than to curse the darkness.....
EMF-L web-site can be found at:
EMF-L archives can be found at:
..................PEOPLE ARE MORE IMPORTANT THAN PROFITS..................
---------- Forwarded message ----------
Date: Fri, 11 Jun 1999 20:26:57 +0200
From: Clas Tegenfeldt
To: "Roy L. Beavers"
Subject: Cars: Rotating static field
At 02:00 1999-06-11 -0500, you wrote:
>Date: Thu, 10 Jun 1999 23:57:41 -0700 (PDT)
>From: Mladen Milidragovic
>To: "Roy L. Beavers"
>Subject: Re: (Guru) Testicular cancer.....
>
>Regarding testicular and prostate cancer, has anybody thought about cars
>as sources of EMF? I did some measurements with 60 Hz Gaussmeter and found
>amazing 5 - 10 mG around and below steering wheels. Yet there is nothing
>that operates on this frequency in a car and the spectrum must be very
>complex. Didn't have opportunity to check Diesel powered cars but I think
>that the picture is similar. Interesting?
The tires are reinforced by a steel wire (cord). That steel is almost always
magnetized during manefacture and carries a static magnetic field. It is
not uncommon or surprising to have 10-100 mikroteslas at 10 cm distance. This
means a static magnetic field inside the car of several mikroteslas. When
you start driving the wheels will rotate and thus also the "static" magnetic
field, inside the car you now have a rotating magnetic field, an alternating
field of low frequency. If you have one or two magnetic pole pairs per
revolution the induced field will have a frequency of about ten hertz
for typical (legal) speeds. The magnitude of the alternating field will
be equal to the static field (of course), only the frequency differs (0 Hz
when still and some hertz when rolling).
By demagnetizing the tires this field can be reduced to 10% or less. The
demagnetizing process is very simple and takes a few minutes per tire.
The demagnetizing has to be repeated every season (6 months) since the
steel may reaquire the magnetized state by mechanical stress. What you need
is a coil with a steel core which creates a very large magnetic leak field,
look at electronic stores or audio studio professional shops (used to
demagnetize studio tape recorders).
The next largest source for magnetic fields inside a car is the wiring
between the alternator and the batttery. Just remove the wire from
the negative connection on the chassis (leading to the battery)
and connect it to the chassis at the alternator. Make sure the
minus wire between the battery and the alternator follows closely
the same path as the plus wire. This reduces the magnetic field from the
pulsating current between the alternator and the battery.
If you demagnetize the tires and rewire the battery as mentioned you can
expect to go from a few mikroteslas down to say 100 nT or even less.
Diesels are better since they lack the ignition system which is a notorius
source for EMF noise.
ps.
1 mikrotesla is 10 mG, 100 cm is 1 m is about 3 feets. (How come you
English speaking people go to the metric system inch by inch slow as
a turtle? ;-)
ds.
Clas Tegenfeldt ,,,
(o o)
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Reprinted with permission of Roy Beavers, http://www.feb.se/EMF-L/EMF-L.html