Capacitance of Toroids Discussion
Date: Wed, 08 Feb 2006 09:04:31 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Capacitance of toroids
Original poster: "Adriano
Mollica" <adriano.mollica@uniroma1.it>
Hello to everyone,
I almost finish the construction of my TC, but i have a little problem. I need
a top load of 29pF, than i think is ok, and i'm going to make it by using a
extensible aluminium pipe, that is pretty cheap and easy to put in a
toroid shape.
My question is, how can i calculate the capacitance of that toroid i'm gonna
build?
i found on internet two different way to calculate it, but both use only two
parametes witch are , in one case: internal diameter and external diameter, or
in the other case: external diameter and size of the pipe.
And of course, i obtained 2 quite different measurements. What i need, is a
formula that use all three parameters toghether: inside diameter(d), external
diameter(D), and size of the tube(x).
do you know the answer?
thanks, Adriano
Date: Wed, 08 Feb 2006 15:05:05 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Capacitance of toroids
Original poster: "C. Sibley"
<a37chevy@yahoo.com>
Isn't interal diameter essentially a function of the external diameter and tube
diameter?
InteralD = ExternalD - 2xPipeD
Baciscally if you have any of the two you can derive the thrid measurement. You
don't need all three...
Curt.
Date: Wed, 08 Feb 2006 15:06:22 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Capacitance of toroids
Original poster: "Gerry
Reynolds" <gerryreynolds@earthlink.net>
Hi Adriano,
You don't want to calculate the capacitance of a stand alone toroid. The
calculation needs to be done in presence of the secondary and surrounding
environment. There are several tools available to do this. JAVATC is the one
that I am familiar with and is a very accurate tool. BTW, inside and outside
diameters, and major and minor diameters are two ways to describe a toroid.
Javatc uses major and minor diameters.
http://www.classictesla.com/java/javatc.html
Gerry R.
Date: Wed, 08 Feb 2006 15:26:17 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Capacitance of toroids
Original poster: Vardan
<vardan01@twfpowerelectronics.com>
Hi Adriano,
It is a complex problem. It depends on the coil dimensions and even some on the
size of the room the coil is in. But there is a program here that does it to
within about 3%:
http://hot-streamer.com/TeslaCoils/Programs/E-Tesla6.zip
It finds the capacitance be working out all the electrostatic fields and such:
http://hot-streamer.com/andrewb/
This is the original DOS based program, but it still runs fine under Windows
too. there are text files in the zip that tell how it works.
There is also an on-line JAVA program here that can do it:
http://www.classictesla.com/fantc/fantc.html
http://www.classictesla.com/java/javatc.html
I have a coil a tune by raising or lowering the top terminal and it works very
well. But you do have to get it set up right to begin with to be sure it will
tune in the range you need. The above program will help a lot there.
Cheers, Terry
Date: Wed, 08 Feb 2006 15:27:15 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Capacitance of toroids
Original poster: Mddeming@aol.com
In a message dated 2/8/06 11:17:38 A.M. Eastern Standard Time,
tesla@pupman.com writes:
Original poster: "Adriano Mollica" <adriano.mollica@uniroma1.it>
Hello to everyone,
I almost finish the construction of my TC, but i have a little problem.
I need a top load of 29pF, than i think is ok, and i'm going to make it by
using a extensible aluminum pipe, that is pretty cheap and easy to put in a
toroid shape.
My question is, how can i calculate the capacitance of that toroid I'm gonna
build?
i found on internet two different way to calculate it, but both use only
two parameters witch are , in one case: internal diameter and external
diameter, or in the other case: external diameter and size of the pipe.
And of course, i obtained 2 quite different measurements. What i need, is a
formula that use all three parameters together: inside diameter(d) ,
external diameter(D), and size of the tube(x).
do you know the answer?
thanks, Adriano
Hi Adriano,
Since D-d=2x there are really only two parameters. Some formulas use
the external diameter of the toroid and some use the center-to-center
diameter, which is, in your notation (D+d)/2. Some formulas are
worked out in inches and others in meters. Make sure you know which
conventions and units the poster of the formula is using. Of course,
these formulas are only exact for a toroid infinitely distant from
any other object and the result will vary with the geometry of your
coil, size and position in the room and proximity of any grounded
object, but they give good first approximations.
Matt D.
Date: Wed, 08 Feb 2006 18:17:25 -0700
From: Tesla list <tesla@pupman.com>
To: tesla@pupman.com
Subject: Re: Capacitance of toroids
Original
poster: "D.C. Cox" <resonance@jvlnet.com>
Use sec coil form dia. x 3 or 4 for major toroid dia., and then use major toroid
dia. to minor toroid dia. of 3:1 ratio to determine correct sizing of toroid.
x 3 gives more streamers and x 4 gives single longer streamers ---
depends on what you like.
Dr. Resonance
>Original poster: "C. Sibley" <a37chevy@yahoo.com>
>
>Isn't interal diameter essentially a function of
the
>external diameter and tube diameter?
>
>InteralD = ExternalD - 2xPipeD
>
>Baciscally if you have any of the two you can
derive
>the thrid measurement. You don't need all
three...
>
>Curt.
>
>
>--- Tesla list <tesla@pupman.com> wrote:
>
> > Original poster: "Adriano Mollica"
> > <adriano.mollica@uniroma1.it>
> >
> > Hello to everyone,
> >
> > I almost finish the construction of my TC, but
i
> > have a little problem.
> > I need a top load of 29pF, than i think is ok,
and
> > i'm going to make it by
> > using a extensible aluminium pipe, that is
pretty
> > cheap and easy to put in a
> > toroid shape.
> >
> > My question is, how can i calculate the
capacitance
> > of that toroid i'm gonna build?
> >
> > i found on internet two different way to
calculate
> > it, but both use only
> > two parametes witch are , in one case:
internal
> > diameter and external
> > diameter, or in the other case: external
diameter
> > and size of the pipe.
> > And of course, i obtained 2 quite different
> > measurements. What i need, is a
> > formula that use all three parameters
toghether:
> > inside diameter(d) ,
> > external diameter(D), and size of the tube(x).
> >
> > do you know the answer?
> >
> > thanks, Adriano