# Re: Isotropic Capacity

```Subject: Re: Isotropic Capacity
Date:  Mon, 26 May 1997 13:47:50 -0400 (EDT)
From:  richard hull <rhull-at-richmond.infi-dot-net>
To:  Tesla List <tesla-at-pupman-dot-com>

At 11:04 PM 5/22/97 -0500, you wrote:
>Subject:  Re: Isotropic Capacity
>  Date:  Thu, 22 May 1997 14:21:48 -0500
>  From:  David Huffman <huffman-at-FNAL.GOV>
>    To:  Tesla List <tesla-at-pupman-dot-com>
>
>
>Theory and Practice. Isotropic capacitance make perfect sense to me.
>If the object is moved infinitely far away from everything else and
>is charged, it will have its minimum 'isotropic' capacitance.
>Isotropic (adj) describes the property, capacitance (noun) that stems
>from isolating the object.
>Actually a sphere is the only object that can be isotropic by
>definition, equal properties in all axes and isotropic is a
>theoretical thing since it can't be done in actual practice.
>In a practical sense there is value in talking about the capacitance
>an object would have if it is moved away from other objects. You just
>can't completely remove it from the universe, right?
>Does a coiler really care if his toroid is 17.8pF, ten feet away from
>any object or that it is 18.2pF 2 feet off the ground? I think he
>does care that a certain size puts him in the ball park.
>Happy parasitic coiling to you!
>Dave Huffman

Dave,

I have never cared a whit about the small differential you mention
above,
personally as I design by the doing.

For the mathematically hyperactive, however, the above is just another
big
ole snare to their computational feet.  Their precision of prediction is
lost. one or two puff can really swing a small system though many many
tens
of kilohertz where the resonator coil is many millihenries!

Couple the failure to determine the real toroidial capacity "in place"
along
with all the other little non-linearities among them, the ionized sheath
about a working system, and these guys are doing good to really pin much
of
anything down about the finalized working systems resonant frequency!

So you see, their concerns are really quite valid, on paper.  (which is
where many of them seem to do the bulk of their coiling.) * remark in
paranthesis might sting a bit but is nonetheless true for the most part.

Richard Hull, TCBOR

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