Re: [Ee] Field mill

I certainly could spin up a design for that, but I'd just rather buy
something that already exists.
Time on the bench vs time out doing what I'm wanting to do.. I'm getting
old. :)

Bob:  Thank you!!  I guess there are Hen's toothbrushes after all!!

I checked, and the output impedance of the mill is 1k, so I have +/- 15mA
to work with. I was thinking they wouldn't run such a low impedance, but I
was wrong.

On Fri, Jun 6, 2025 at 9:43 PM Allen Mulvey <[email protected]> wrote:

> Could you use a microcontroller to send the data over a mesh or other
> radio signal to a digital decoder. I use MQTT over both mesh and WiFi.
> (In the past I have also used NRF24L01+ radios.)Single element data
> makes for a very small packet and sending over very short intervals can
> give almost real time visibility. Here is an example:
> https://meshgauges.mulvey.us/
>
> Allen Mulvey
>
> On 6/6/2025 11:02 PM, David VanHorn wrote:
> > 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.
> >> --
> >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> >> View/change your membership options at
> >> https://mailman.mit.edu/mailman/listinfo/piclist
> >>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> https://mailman.mit.edu/mailman/listinfo/piclist
>
-- 
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
https://mailman.mit.edu/mailman/listinfo/piclist