How fast does the maltese cross turn?
Regards.
Max. K 4 O DS.
Email: m...@maxsmusicplace.com
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----- Original Message -----
From: "Neville Michie" <namic...@gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Wednesday, June 25, 2014 10:46 PM
Subject: Re: [time-nuts] Loran, GPS, Lightning, Timing
Is anyone using a field mill?
I have always been going to make one.
It consists of a horizontal metal plane with a conducting button on the
surface
which is insulated from the ground plane.
A metallic maltese cross driven by a motor alternately covers and uncovers
the electrode
exposing/not exposing it to the sky.
The electrode button has capacitance to ground which drops its impedance,
but across that impedance is an AC voltage proportional to the ambient
static field.
A typical field in fine weather is 300 Volts/metre so the signal is not
trivial.
You should be able to make a field mill that works continuously except
when
actually shorted by rain.
This is not a very high impedance device, and should show many marvellous
things
as the clouds float over you.
You can calibrate it with a metal plate, say 12 inches above it with 50
volts on it.
That should produce a uniform field on the mill.
cheers,
Neville Michie
I know you are talking about measuring lightning strikes but if you get
the
impedance high enough, you can actually measure the earth's electric
field.
(It is about 200V/m if I recall properly.) Interestingly it is affected
by
the solar flux and solar wind.
--
Brian Lloyd
Lloyd Aviation
706 Flightline Drive
Spring Branch, TX 78070
br...@lloyd.com
+1.916.877.5067
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