Re: Multiple toroid capacity

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi Scott,

All you do is set the toroid on a sonotube or suspend it with string and 
measure it.

However, there is always, and will always be,a "catch".  The wire going to 
ground.  In order to measure the capacitance you need a path to ground 
(like a wire) that will also have a substantial capacitance.  In order to 
take the real measurement, you need to hook the meter between the toroid 
and ground.  There is not a way to measure the capacitance without hooking 
a wire to it, which will mess things up.

We can do it with a computer an all that, but what is the point since a 
free floating capacitance in space is not useful to us without a wire going 
to it.  You "always" have to consider that wire leading to the toroid "anyway".

DC's "rule of thumb way" to get to a "ball park figure" is as good as 
any...   There are all kinds of theoretical ways to find the real 
capacitance of an isolated body, but the uses for that number are all 
theoretical too...  If you are going to use it, you need to hook a wire to it.

Maybe a situation like a vandegraff (SP) generator where you can measure 
the potential would be a way to do what you want.  If you know the amount 
of charge you add and the resulting voltage on the top terminal, you know 
the capacitance....  But a computer is easier ;-))

Cheers,

         Terry


At 12:49 PM 4/13/2003 -0700, you wrote:
>Dr. Resonance -
>
>When you directly measured the effective capacitance of a topload using a
>Wavetek LCR meter, can you describe the test setup you used? Was the toroid
>suspended in free air at operating height, or mounted on the secondary? How
>was the LCR meter connected to the toroid? Was a ground plane used in the
>test setup?
>
>I'm interested in your method of directly measuring toroid capacitance as
>previous searches for a measurement method yielded only "indirect" means
>(measure resonant frequency of bare secondary, add topload, again measure
>resonant frequency and derive the topload capacitance from change in
>frequency).
>
>A simple, reliable, accurate means of directly measuring toroid capacitance
>would be useful, especially for odd-shaped or "compound" toploads consisting
>of stacked toroids, corona ring plus a sphere, etc.
>
>Regards,
>Scott Hanson
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Sunday, April 13, 2003 11:39 AM
>Subject: Re: Multiple toroid capacity
>
>
> > Original poster: "Dr. Resonance by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>
> >
> >
> > Due to the "shielding effect" when multiple toroids are used the value is
> > always less than the value of two separated individual toroids added
> > together.  With two toroids a rule of thumb is you deduct from the total
> > separate added capacitance approx. 50% of the value of a single toroid's
> > capacitance.  This will give you a good ballpark figure assuming both
> > toroids have the same physical size.
> >
> > If the sizes are different then it's usually easy just to measure the
>total
> > with a Wavetek or equiv. meter.
> >
> > Dr. Resonance
> >
> > Resonance Research Corporation
> > E11870 Shadylane Rd.
> > Baraboo   WI   53913
> >
> >  > When running stacked toroids on a coil, how is the total combined
> >  > capacity of them calculated?  Surely it isn't as easy as adding
> >  > together the individual capacities...or is it?
> >
> >
> > ---
> > [This E-mail scanned for viruses by SURFSIDE INTERNET]
> >
> >
>
>---
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