Re: Big top loads

["Malcolm Watts" <malcolm.watts-at-wnp.ac.nz> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi Kurt,
            The terminal I was speaking of is basically a filled-in donut - 
i.e. a toroid without a hole. I make mine using polystyrene foam 
from rubbish skips and apply several coats of cooking foil using a 
polystyrene contact adhesive. They're a bit vulnerable to being 
knocked around but they work.
 
Regards,
Malcolm

On 6 Jun 00, at 21:29, Tesla List wrote:

> Original Poster: "Kurt Schraner" <k.schraner-at-datacomm.ch> 
> 
> Hi Alan, Malcolm, all,
> 
> about the similar idea came to me, when I had a look at the
> capacitance-formula for a toroid in a TC-design spreadsheet,
> seeing it was dominated by the main diameter, and the cord
> diameter beeing of only minor influence. It is not quite clear to
> me however, how you keep the outer curviture high enough in the
> z-direction (coil axis) if you are using a disk. Think I don't
> understand your construction well enough. I'm quite interested in
> your design, because for my bigger hobby-coil "Black & White"
> (15.75"dia./70"length) I'm in need for a big topload as well. The
> process of building this coil can be seen at:
> 
> http://home.datacomm.ch/k.schraner/index.htm , under the heading
> "equipment".
> 
> In fact, my toroid of diameter 63"(1.6m) x cord diam.15.75"(0.4m)
> is already in the make, and will be at me this week. It is made
> by a workshop (Iraklis Galanis, Basel), where they make
> insulations, for heating systems, chemical plant tubes etc.. The
> toroid is made, according to my specifications, and at a very
> reasonable price (SFr.400 = ca.  $235 ), including the design. I
> have already good experience with this kind of toroids, which
> kind can be seen at:
> 
> http://home.datacomm.ch/k.schraner/tc8inch.htm
> 
> In some cases this might be an alternative to the flat-disk
> toploads you have in mind, and Malcolm has in use ?
> 
> Kurt
> 
> 
> 
> Tesla List schrieb:
> > 
> > Original Poster: "Alan Sharp" <AlanSharp-at-compuserve-dot-com>
> > 
> > Greetings all,
> > 
> > I'm looking at building a much larger topload for
> > my coil, and I was considering moving away from
> > to toriod to a disc shape (a filled in toroid if you like)
> > 
> >  ()----()   becomes  (PLATES)
> > 
> > So I will still have the outer curviture to hold back
> > the breakout.
> > 
> > Am I right in thinking:
> > firstly that the capacitance of this disc will be almost
> > the same as for a toriod of the same dimensions?
> > 
> > secondly the disc will electrostatically shield the
> > the secondary exactly as a toriod would?
> > 
> > Alan Sharp (UK)
> 
>