Re: [TCML] Poly thickness

["David Rieben" <drieben@xxxxxxxxxxx>]

Hi Bart,


Snip>>>>

----- Original Message ----- 
From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, July 04, 2008 11:42 AM
Subject: Re: [TCML] Poly thickness


> Hi David,

> DC and AC resistance are half that of the closewound.
> Q increases slightly.
> Reactance is half.
> Frequency doubles.
> Distributed capacitance remains the same for both.
> Inductance is reduced by a factor of 4.


Ok, I agree with all but the distributed C. Maybe I don't
understand the terminology of the term "distributed capa-
citance" but I always assumed that it referred to the capa-
citance of what is formed by the dielectric qualities of the
wire's insulation between each adjacent winding (and the 
air, which would significantly reduce the this distributed C, 
especially with a space wound coil, wouldn't it?) Now I'm 
confused because I seem to remember hearing the idea that 
the distributed C was INCREASED by close winding the 
secondary coil (and that was supposed to be a bad thing),
which seems backwards now that I think about it. It seems
the distrbuted C would be dramatically reduced by space 
winding the secondary coil, since you are in effect incresing the 
dielectric thickness and also dropping the dielectric constant
by adding more air (which has a dielectric K of 1) to the dielectric 
Isn't the C of a dielectric system determined by C = K(.2249 x A/T)
Where K is the dielectric constant, A is the dielectric area, in sq. ins.,
and T is the dielectric thickness in inches, and C is in uFd? Help :^/

> The closewound coil will attempt to charge the topload to double the 
> voltage of the spacewound coil. This is significant. I ran both coils 
> looking at the voltage distribution (changing turns only). Here's how it 
> came it out (btw, default coil in Javatc).
>
> http://www.classictesla.com/temp/closewound.gif
> http://www.classictesla.com/temp/spacewound.gif
>
> In order to achieve the same performance as the closewound coil above, 
> you would have to double diameter, length, turns, toroid, primary, etc. 
> for the same spacewound ratio.
>
> I don't see an advantage and this larger coil would be even better 
> closewound.
>
> As far as racing sparks? Well, I speculate both coils would be similar. 
> The volts per turn hasn't changed from at least that standpoint and both 
> distributions are rather linear due to their h/d.

Agreed.

> Take care,
> Bart

Happy 4th and many sparks,
David
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