Author Topic: Field Mill or other ways to measure atmosphere voltage gradient  (Read 279 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 Old Tele man

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #3 on: May 11, 2018, 07:20:34 PM »
First, read up on "how" capacitors work, then "how" air behaves similar to dielectric in capacitor.
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Offline Jstx

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Re: Field Mill or other ways to measure atmosphere voltage gradient
« Reply #4 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.

 

anything