Re: bipolar coil design

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Malcolm Watts" <m.j.watts@xxxxxxxxxxxx>

Hi Gerry,

On 22 Mar 2005, at 21:28, Tesla list wrote:

> Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Paul,
>
> Good to hear from you.  I was just thinking about your expertise in
> resonant modes and the next post was yours.
>
> >Original poster: Paul Nicholson <paul@xxxxxxxxxxxxxxxxxxx>
> >
> >I think the primary coil design must be the most tricky bit of
> >the whole project.   Not least of which because that nice symmetry of
> >the voltages, with zero in the middle, is only an ideal case. In
> >practice the secondary voltage will find its own balance - at a point
> >dependent on how well matched the end capacitances are, and on how
> >evenly the streamers are formed at each end.  The zero, therefore,
> >may be drawn away from the center of the coil by any asymmetry
> >present - such as drawing an arc from one end to ground.
> >
> >This is not good news for the primary, and to cope with this
> >inevitability, it would be a good idea to build in a lot more
> >voltage breakdown capability than normal.  If the inner diameter of
> >the primary was raised to say 12-14", the inductance increases, the
> >coupling reduces, and the voltage breakdown tolerance is raised.
> >Putting in the 3" gap is a good move - it reduces the otherwise
> >excessive coupling and increases breakdown tolerance.
>
> One could also put some acrylic tubing between the primary and
> secondary as well I would think.
>
> Also, one would design the primary for a 1/4 wave design and the only
> difference between 1/4 and 1/2 wave operation would be that haft of
> the primary energy would find its way into the top load of one of the
> 1/4 wave coils.  If this is correct, than it seems like the topload
> voltage predicted by JAVATC would be 41% too high.  One might want to
> take this into account to make sure that the topload breaks out.
>
> Gerry R.

Some time ago I built a small tabletop system. The primary cap was
charged by a SM cap charger run from a small wallplug pack. To
obviate the need for a ground I used a second resonator as a
parasitic ground. Power sharing between the two resonators depended
mostly on relative toploading. Primary tuning was for signle
resonator operation and not changed whether I used the second
resonator as a ground or the ground itself.

Malcolm