Re: PC board primaries

["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 Robert,

On 10 Dec 2001, at 11:54, Tesla list wrote:

> Original poster: "R Heidlebaugh by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>
> 
> on 12/10/01 8:09 AM, Tesla list at tesla-at-pupman-dot-com wrote:
> 
> > Original poster: "Barton B. Anderson by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
> > 
> > Hi All - 
> > 
> > An idea (not sure if it's been thought of - I haven't paid close
attention).
> > 
> > For a double-sided pc board, the top and bottom trace can be slightly
> > overlapped. This would make it possible to simply etch/cut simple circlular
> > traces (a gap must be cut between each circle to prevent a shorted turn). A
> > feed through between upper and lower circle traces can link each turn.
> > 
> > Something like this: You have to use your imagination a little.
> > 
> > 1     3     5     7     9
> > ----  ----  ----  ----  ----
> > |  |  |  |  |  |  |  |
> > ----  ----  ----  ----
> > 2     4     6     8
> > 
> > Space saving as well considering this approach:
> > 1     2     3     4     5     6     7     8     9
> > ----  ----  ----  ----  ----  ----  ----  ----  ----
> > 
> > Anyway, I was just thinking about the ease of simple circles instead of a
> > continuously growing traces.
> 
> AS I REPLIED BEFORE,PC board coils are subject to high frequency harminics
> and require neutralizing to avoid TVI.

Could you explain that answer in more detail please? How much 
difference is there between an air insulated spiral and one sitting 
on copper/fibreglass laminate at TC frequencies? And how would you go 
about neutralizing such a coil?

 Single sided coils work well and also
> double sided coils with each winding overlaping each other. Winding to
> winding capacitance is high with double sided coils and must be corrected
> for. Single sided coils have extreamly low capacitance, and must be
> compensated for at the other extream.

Again, how would one compensate? I would have thought that turn-turn 
capacitances were insignificant compared with the primary capacitance.

Regards,
Malcolm

 Coils are made with helical winding
> spirals or circular turns steped out to the next outer wind at each loop
> end. Both work. square box coils work, but harmonics are an even greater
> problem with lower "Q" coils. Edge emmisiom is no problem as suggested by
> another TC fan. Make shure your winding to winding spacing is sufficent.
> Standard 60 mill glass board will hold the output of a 15KV NST with no
> problem, but keep at least 1 in from the board edge.
>    Robert  H
> 
> 
> 
>