Re: [Ee] Field mill

Not worried in the slightest about fields around the output line. If I were
to use copper cable it would be shielded, and the output voltage is only
+/-15V so the field that the detector sees would be uV/m at best.

Imagine lightning striking the field mill, and I have a copper connection
back to my car.....  Conversely a strike on my car, if I am holding a cable
that extends out from the car could also be fatal.
Even the leader discharge (just before lightning strikes, and there are
usually many leaders before a strike, only one usually makes contact) could
be fatal if I were holding or even nearby a cable connecting back to the
mill.

Fiber optic could work, but that seems expensive, and would of course
require some sort of encoder/decoder system.

A normal panel meter is going to be very hard to read at a distance, see
above for concerns about lightning strikes on the mill.  That's why I'm
thinking LED bargraph. Highly visible, and no cable to put me at risk.

Lightning photography is a dangerous hobby. I've got significant experience
and training in severe weather observation under a PhD Meteorologist.

The field mill will indicate about 200V/m on a nice day, then when charged
clouds are near the field will increase substantially. (2000..5000V/m
typically, could be higher)  A strike will collapse the field for a few
seconds, while it builds up again.

Prior to this acquisition, my only available data was "Do I see leaders
forming nearby?" (EASY to miss) and "Are the antennas on my car glowing?"
(in which case I should already be somewhere else!!) and I've had that
happen.
I'm prepared to abandon the gear if necessary, but I'd REALLY rather not.


I have no idea where to find one, but a LARGE analog meter, center zero, of
10 to 100uA could work. It would have to be illuminated.  I know they used
to make such for classroom use, but probably hen's toothbrushes today.
Visible at 50' or more, in the dark, is the key.

When they launch rockets to trigger lightning, they are sitting in a
grounded faraday cage building, all the electricals are at the pad, and the
"cable" is an air hose using pressure to close the remote switch.
I am NOT trying to do this in the link below, rather I am trying to enhance
my safety in the field by knowing when strikes are likely to occur near me.
https://www.youtube.com/watch?v=9wlU6Typ9Y4  There was a much better video
on the weather channel, but apparently they've retired it.
A field mill is used in these systems to determine the optimum launch time.



On Fri, Jun 6, 2025 at 7:17 PM Jason White <
[email protected]> wrote:

> Shielded differential pair? Coax with ground on outer and signal on inner?
> Fiber Optic?
>
> Why are you worried about the output line generating a field if you are
> already running power to it? Do your power connections need to be shielded?
>
> It seems like it would be straightforward to use a shielded cable and read
> it with a handheld meter with a backlight.
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