Re: Toroid capacitance

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 8/8/01 1:50:10 PM Eastern Daylight Time, tesla-at-pupman-dot-com 
writes:

> Could You explain me where I'm making a mistake?
>  (Toroid surface is not smooth. It's made of notched aluminium pipe. Is
>  capacity of such toroid larger or smaller, than capacity of smooth, this
>  same size toroid?)
>  
>  Thanks 
>       
>  
>  Kamil Kompa

Kamil,

The capacitance of a toroid when measured in that manner
will depend on the toroid's distance from other items in the
room.  To measure the isotropic capacity more accurately,
the toroid should be suspended on a string in a huge room,
with nothing nearby.  Then the capacitance will closely
match the Wintesla results.  Note also that the toroid's
effective capacitance will be less when it's installed on
the secondary due to shadowing and other effects.  
Terry has a program (E-tesla-6 I think) which compensates
for the shading effects and will give the approximate true
working capacitance.  Generally a 30% reduction in
capacitance is probably about right.  So for a 17pF toroid,
figure you'll actually get 12 or 13 pF or so.  (ballpark)

Smooth or corregated doesn't really matter.

John Freau