Author Topic: Field Mill or other ways to measure atmosphere voltage gradient  (Read 598 times)

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Offline DaleReid

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As a glutton for punishment and not enough to do already, I'm once again thinking of how to measure the voltage gradient of the atmosphere.

Boltek had an amateur field mill for a couple thousand dollars.

Campbell Scientific makes one, which is about six thousand. 

I've found a couple YouTube videos of a guy making one with a plastic DVD container and a motor, but is that a good start or not?  A couple high school kids had a project over in Europe I believe, where they made a transconductance amplifier and an elaborate metal container withe concerns about impulses from the motor to be shielded and so on.

Maybe this isn't something for which there is a workable solution unless one's pockets are extremely deep.  And of course it adds little to the situation of weather observation.  But it seems pretty cool to watch the gradient as thunderstorms approach and recede.

Has anyone seen any home built solutions, or have had experience with anything like this if they were similarly interested and already looked at some project?

Thanks for any discussion or leads.  Dale

PS, if you have a Campbell Scientific Field Mill that you are going to toss out, please call immediately!
Just teasing.
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Offline Ian.

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #1 on: May 11, 2018, 01:46:11 PM »

http://www.cdarc.org.uk/downloads/presentations/Measure_Earth_Electrostatic_Field.pdf

At my local radio club Peter gave a presentation and demonstration of one he built.
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Offline DaleReid

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #2 on: May 11, 2018, 05:25:17 PM »
Ian, thanks for the pdf and the links.  I will digest more as I have time to print the pdf out and look at the schematic.

I think that I've seen the device in the Jim Campbell host site before. 

Some thoughts I've had is about how fast the motor needs to turn, or is the speed merely a function of what speeds of motors are available?

I think the the Campbell Scientific device used a stepper motor to rotate the chopper into position, then reversed and rotated it out of position. I've never seen a real one, so I don't know if it chatters back and forth, or cycles every 1/2 second or so.

Lots of stuff to be answered.
Thanks again.  And anyone with real world experience is welcome to join the sharing of info.
Dale
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Offline Jstx

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #3 on: June 10, 2018, 10:38:13 PM »
As a glutton for punishment and not enough to do already, I'm once again thinking of how to measure the voltage gradient of the atmosphere.

Boltek had an amateur field mill for a couple thousand dollars.

Campbell Scientific makes one, which is about six thousand. 

I've found a couple YouTube videos of a guy making one with a plastic DVD container and a motor, but is that a good start or not?  A couple high school kids had a project over in Europe I believe, where they made a transconductance amplifier and an elaborate metal container withe concerns about impulses from the motor to be shielded and so on.

Maybe this isn't something for which there is a workable solution unless one's pockets are extremely deep.  And of course it adds little to the situation of weather observation.  But it seems pretty cool to watch the gradient as thunderstorms approach and recede.

Has anyone seen any home built solutions, or have had experience with anything like this if they were similarly interested and already looked at some project?

Thanks for any discussion or leads.  Dale

PS, if you have a Campbell Scientific Field Mill that you are going to toss out, please call immediately!
Just teasing.

'voltage gradient's', yeesh. How about a couple of very sensitive digital VM's a hundred yards apart with a common ground and some kind of rapid logging? Bet Fluke has something.

Haayl, up in the Texas Panhandle if you hear some thunder rumbling in the distance, ya jes stick yer arm out ta winder an watch an feel the hairs on yer arms stan up.

I ain't never been anywhere that I felt those arm hairs (and on me haid to) twitchin' with most every thunderstorm that rolled through up there.
Had it happen a few other times at home and on the boat (that was scary, at sealevel, was nervously looking for good ol' St. Elmo).
At home I was standing in the garage about eight feet inside the open door talking on a cellphone and watching a really violent thunderstorm all around. All of the sudden there was a blinding flash of light, a noise like a battleship salvo (chest concussion level), and all my hair just jumped straight out; all at once. Yeeeow! Never did find where it struck, but it had to be within a few hundred feet.

Offline SLOweather

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #4 on: July 20, 2018, 06:44:59 PM »
Hey, DaleReid,

I was cleaning out the garage and sorting boxes and ran across my aging copy of "The Amateur Scientist, Projects from The Scientific American" by C. L. Stong. it's a compilation of his SI columns from the 50s and 60s (publishing date on my copy is 1960).

I've been going through it, and marveling at some of the stuff he and his correspondents were doing back then (several seismographs, including one that uses a water well, "exploring the atom at home", "how to tranquilize a rat". "a universal sundial" and lots more.

In there is one article, "AN ELECTRONIC WEATHER FORECASTER" which turns out to be a sferics and electric field measuring device. It sounds like something you might be looking for.

Quote
With the exception of the electrical-pen recorder, the equip-
ment for measuring field intensity and making sferic counts is
relatively inexpensive. The sferic detector is essentially a special
radio receiver equipped with a means for counting short pulses
of current [see Fig. 119] The antenna consists of a bare copper
wire at least 20 feet long suspended 10 feet or more above the
ground between glass insulators. It serves the dual purpose of
picking up sferics and sensing field intensity.

A sferic signal excites the tuned 456-kilocycle transformer, and
the resulting oscillations are amplified. The train of amplified
oscillations is then rectified and used to trigger a pulse-forming
circuit. The output is averaged in a vacuum-tube voltmeter cir-
cuit. The antenna should be equipped with a lightning arrester;
as a further protection the receiver is equipped with a choke coil
designed to block damaging bursts of energy at high frequencies.

Here's the schematic, copied from a PDF of the book on-line. Note in the bottom left the meter for displaying the local field intensity.



It would be an interesting project to convert this from hollow state to solid state electronics. :)

If you are interested in the entire article, or perusing some of the other projects, the entire book can be downloaded free in various formats at

https://archive.org/details/TheAmateurScientist

You may have to download it in more than one format to get everything. The PDF with text might be the best. The raw text version was missing some text.



Offline DaleReid

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #5 on: July 20, 2018, 08:17:56 PM »
Holy cow, that series really set the standard for the magazine at the time.  Nothing came close.  I had a few of the Sci Am that I got from a used book store in Madison, WI, but wouldn't have collected them all (even at 50 cents/apiece).

This book is a treasure, and you've hit some memory chords that haven't been struck in decades, or close to half a century at best.

I have a ham radio friend equally versed in solid state (he helped with memory on the original Cray I series) and vacuum tube stuff.

He's retired and perhaps he'd gander at the schematics and say, hey this miight be a project.  Of course it might be way more than a project.

As an aside, in high school we were building the He-Ne CW laser, but never could get the money for the diaganol and totally reflective mirrors.  We blew the glass several times and were pretty confident given more funds we could have made one, back at a time that most universities didn't have but a couple and they were darned expensive.

Wow, what memories!
Thanks loads.  I'm off to download.  Dale
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Offline Bushman

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #6 on: July 20, 2018, 08:23:43 PM »
Cool old stuff for sure!  Modern version here?  http://www.techlib.com/electronics/lightning.html

Offline SLOweather

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #7 on: July 20, 2018, 10:56:32 PM »
Cool old stuff for sure!  Modern version here?  http://www.techlib.com/electronics/lightning.html

This sferics receiver from the same site might be closer to the original project's sferics section.

http://www.techlib.com/electronics/spherics.htm

But DaleReid started out wanting something to measure the electric field.
« Last Edit: July 20, 2018, 10:59:03 PM by SLOweather »

Offline miraculon

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #8 on: July 21, 2018, 08:41:28 AM »
I found this a few years back: Feldmühle/Field-mill for 60 – 170 Euro . Here is the link to the PDF: http://members.inode.at/576265/fieldmill.pdf

The link in the PDF points to a page (without a lot of detail) with a couple of other interesting links covering the field mill.

The first is at http://www.qsl.net/dh1stf/ This is in German, but Google translate seems to work OK.

The 2nd one http://www.hcrs.at/ has the "Feldmühle A meter for electric fields" under the Elektrotechnikseiten page. This one is also in German, so I used Google translate for this one as well. This page seems to agree with the PDF.

I considered buying this as a kit, but it seemed to be a dead project at the time. There isn't any reason that the PCBs could be made up and you could fabricate your own.

Greg H.


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CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline DaleReid

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #9 on: July 21, 2018, 10:46:40 AM »
Greg,
the first link to a pdf fails, but would be of interest if it contains detail.  Do you still have that in your collection and could share?
Dale
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Offline miraculon

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #10 on: July 21, 2018, 11:32:39 AM »
It's a 2MB file, so I'll try to come up with something. Can you reach the basic website http://members.inode.at/576265/?  Or, is it just a PDF problem?

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline DaleReid

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #11 on: July 21, 2018, 03:26:59 PM »
Interesting that the second place was not reachable, but when I opened the URL in Chrome rather than Firefox, it did just fine.

The problem is this looks like a project that I dearly would have loved to put some bucks towards, and while the boards and layout are helpful, just like Blitzortung having a kit rather than going it alone.

Darn.  You said the link or project seems dead.  I wonder if there is any way to reach the folks that were involved, but then I don't speak German.  I'm hoping to find some lead.  Couldn't have been any more perfect than this, for those who wanted to fiddle with this.

Thanks for the info, there are plenty of circuits to study and figure out, along with seeing if there are things that they did which would make a worthwhile project.

I am indebted.  Thanks   Dale
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Offline SLOweather

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #12 on: July 25, 2018, 02:56:38 PM »
I was looking at the schematic I posted from the Stong book PDF and realized it was incomplete.

Here's a cropped, reduced, and enhanced photo from my copy of the book. PM me if anyone wants to see the full res version.


Offline DaleReid

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #13 on: July 25, 2018, 03:28:51 PM »
Thanks, I heard from my electronics genius friend that the circuit was goofy, with some tube thingie he knew about that seemed to be missing.  I wouldn't have known without doing a lot of study.

I appreciate the copy you posted.  Saving now.

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Offline SLOweather

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #14 on: July 25, 2018, 03:46:24 PM »
Cool. If you or he wants the full res image (the one I posted was reduced to 33%), pm me an email and I'll send it.

Thanks, I heard from my electronics genius friend that the circuit was goofy, with some tube thingie he knew about that seemed to be missing.  I wouldn't have known without doing a lot of study.

I appreciate the copy you posted.  Saving now.