# Re: Primary spacing on large coil.

```Tesla List wrote:
>
> >From rwstephens-at-ptbo.igs-dot-netMon Apr 29 21:09:29 1996
> Date: Mon, 29 Apr 1996 13:07:38 -0500
> From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: Primary spacing on large coil.
>
> >>From larrycg-at-intele-dot-netSun Apr 28 22:06:15 1996
> >Date: Sun, 28 Apr 1996 10:17:51 -0600
> >From: "Larry C. Gardner" <larrycg-at-intele-dot-net>
> >To: tesla-at-pupman-dot-com
> >Subject: Primary spacing on large coil.
>
> Larry Gardner wrote,
>
> >I am currently in the process of building a large Tesla coil.
> >It will have an input of 50KV at 100mA.  The primary capacitance is
> >12.5nF, and will resonate at 120kHz. The secondary has a diameter of 15
> >inches.
> >       The problem here is how far apart do the primary winding need to
> >be in a large coil?  In the smaller coils built I know that primary
> >sapcing was recommended to be from 3/8 to 1/2 of and inch.
>
> >       Any help would be greatly appreciated.
>
> >Larry Gardner
>
> >"The present is theirs, the future, for which I really worked, is
> >mine"-Nikola Tesla
>
> Larry,
>
> Break timing  jitter and dwell start to deviate wildly  and
> become increasingly hard to control with conventional rotary breaks at
> such voltages.  The only reason I can figure that you must wish to
> try this is to get higher power from a very high voltage, small value
> capacitor that you must have lucked upon and that you also have a
> 100mA, 50 kilovolt transformer.  I think the extra problems that you
> will have with  your break merely to achieve 5 kilowatts, commonly
> achieved by simpler means, will diminish the value of this exercize.
> However,... if you want to go to that trouble to charge a LARGE value
> capacitor at 50 kilovolts with say 1 amp or more,  I'd say go for it before I
> do so and maybe I can learn from your mistakes!
>
> Happy coiling!, rwstephens	In the coil under construction I have surplus mica caps, at
approximately 6nf and 120KVDC.  The power supply is being build by a
freind for the cost of parts.  The gap being experimented with is a
multiple gap, as diagrammed in Tesla's red book and The Fanstastic
Inventions of Nikola Tesla.
The one question I still have is what do the primary winding
spaceings need to be on a coil this size?

Larry

"The present in their's, the future, for which I worked, is mine"
-Nikola Tesla
```