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Re: Isotropic secondary capacitance
From: bmack[SMTP:bmack-at-frontiernet-dot-net]
Sent: Monday, September 08, 1997 8:31 PM
To: Tesla List
Subject: Re: Isotropic secondary capacitance
Thanks malcolm!
Have you confirmed this formula with a few coils yet?
Jim M
---------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Subject: Re: Isotropic secondary capacitance
> Date: Sunday, September 07, 1997 11:51 PM
>
>
> From: Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent: Sunday, September 07, 1997 5:05 PM
> To: tesla-at-pupman-dot-com
> Subject: Re: Isotropic secondary capacitance
>
> Hello Jim,
>
> > From: bmack[SMTP:bmack-at-frontiernet-dot-net]
> > Sent: Saturday, September 06, 1997 10:07 PM
> > To: tesla list
> > Subject: Isotropic secondary capacitance
> >
> > Fr Tom,
> >
> > A very astute observation on the nature of distibuted
> > capacitance animal! That surface area capacitance could
> > calculated(?) using the "free air capacitance" equation for
> > the coil area and the standard "plate equation" with curvature
> > of the wire considered, to find the inter winding capacitance.
> > Am I on track here?
> >
> > Now, are these two entities in parallel or series with respect to
> > each other? Maybe a little of both? Ouch!
> >
> > When I run very low power tests to tweek the systems, placing ones
> > hand near the coil body has as much effect on the resonance as getting
> > near the top cap. This in my opinion clear evidence of isotropic
activity.
> >
> > With a little help from our friends, there might even be a way to
reliably
> > predict the distributed capacitance mathematically!
>
> There is indeed!! You'll be pleased to know that after a three month
> search while researching a TC article for a magazine, I found it. It
> is Medhurst's formula:
>
> C = HD pF where D is coil diameter in cm and H is a factor that
> follows the law:
> h/d = 2 H = 0.51
> h/d = 5 H = 0.81
> Interpolation is linear for this h/d range. H bottoms out at 0.46 for
> an h/d = 1 (which as fate would have it was the final form Tesla's
> extra coil took :) The tabulated values for H remove the complex
> mathematics from the formula.
>
> Malcolm
>
>
>