Re: Toroid Construction - Need something good . . .

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Antonio,

On 22 Jul 2002, at 16:37, Tesla list wrote:

> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
> 
> Tesla list wrote:
> > 
> > Original poster: "Allanh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <allanh-at-starband-dot-net>
> > 
> > It doesn't matter what metal is used for the top load, as long as it is a
> > solid piece, no hole in the middle, which would form a single shorted turn
> > and sink lots of current.
> 
> A hole in the middle doesn't make any difference. A shorted turn at that
> place, with very little series resistance, just changes slightly the
> secondary inductance, without adding significant losses.
> 
> By the way, I am making a toroid by gluing a stack of thin plywood 
> disks cut to calculated sizes. I will cover the resulting toroid, 
> after finishing its surface (without a hole in the middle) with 
> aluminum tape, or maybe I will use it as a form for metal spinning.
> 
> I was using e-tesla6 to calculate the required size for this toroid,
> but noticed that it assumes a toroid with a hole. Some simple trick
> to make it consider a holeless toroid?
> 
> Antonio Carlos M. de Queiroz

I once tried "filling in" a standard toroid by covering the top and 
bottom with circular Al plates to check for a change in capacitance 
when it was sitting on a secondary. It appeared to make little 
difference and then I realized that the bulk of the capacitance was 
corresponding to the highest electric field strength - like from the 
outer sides.

Regards,
malcolm