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Re: Top Toroid
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Hi Group,
OK I have a capacitance meter and several toroids, can they be measured
directly or do you put them on top of an inductor and from the freq. shift
calculate the capacitance?
__ __
/ \ / \
\__/ \__/ does the capacitance change much if the toroid
__ ___ __
/ \
\__ ___ __/ is filled in the middle. I would think the E-field looks
similar.
Dave Huffman
----------
> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: Re: Top Toroid
> Date: Friday, January 31, 1997 12:05 AM
>
> Subscriber: rhull-at-richmond.infi-dot-net Thu Jan 30 22:56:39 1997
> Date: Thu, 30 Jan 1997 18:27:28 -0500 (EST)
> From: richard hull <rhull-at-richmond.infi-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Top Toroid
>
> At 09:10 PM 1/29/97 -0700, you wrote:
> >Subscriber: c604313-at-showme.missouri.edu Wed Jan 29 20:57:23 1997
> >Date: Wed, 29 Jan 1997 13:33:57 -0600 (CST)
> >From: c604313-at-showme.missouri.edu
> >To: tesla-at-pupman-dot-com
> >Cc: Tesla-list-subscribers-at-poodle.pupman-dot-com
> >Subject: Re: Top Toroid
> >
> >
> > Jeff,
> > Here is a small list of Toroids and there capacitance in picofarads:
> >
> > Toroid (height X diameter) Picofarads
> >
> > 3 X 12 12.95
> > 5 X 14 16.08
> > 5 X 20 21.58
> > 7 X 30 32.17
> > 6 X 36 37.18
> > 12 X 36 40.84
> > 8 X 48 49.58
> > 12 X 48 51.79
> > 12 X 60 63.32
> > 20 X 60 68.07
> >
> >
> > The Toroid is measured in inches.
> > One quick remark. try to construct the cap with the least amount of
> >metal just a thin shell of metal is best (aluminum duct tape on 4 pvc
> >joints fitted together works well) The reason being is that the top cap
is
> >also in the midst of the magnetic field that is set up by the primary
ind.
> >If the terminal cap was a solid chunk of metal, the changing magnetic
> >field would set up an E field in the cap and induce current flow causing
> >heating of the Terminal cap which is a waste of energy. you don't want
the
> >toroid to soak up the energy of the magnetic field you want that energy
to
> >be soaked up by your secondary coil.
> > There is a good toroid home brew description on Bill Beaty's Tesla
> >web page.
> > enjoy!
> > --Bert S.
> >
> >
> >
>
> Bert,
>
> I trust these are calculated values!!! I can almost tell due to the fact
> they are all in error from real world, honest to God, measured values. A
> true, relative isolated toroid is usually about 25-30% lower in capacity
> than the calcs say it is. My 12X3 spun unit is 7.8pf and my 5X20 is 15.1
> pf. put them on a coil and they can appear to be even more than
calculated!
> It's a crap shoot! The thrust is that the math isn't even close for any
> form of critical engineering purposes. Especially on small toroids.
>
>
> Richard Hull, TCBOR