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Re: Best Primary Coil

Subject:    Re: Best Primary Coil
      Date: Thu, 24 Apr 1997 22:06:27 -0700
      From: Gary Weaver <gweaver-at-earthlink-dot-net>
        To: Tesla List <tesla-at-pupman-dot-com>
References: 
           1

> > Also, for tuning, it has always seemed to me that it would make more
> > sense to tap *in* instead of *out* since the inner turns have less
> inductance
> > per turn that the outer turns, and so tapping *in* would give one greater
> > control over the total inductance. Actually, I guess that it would make
> > the MOST sense to be able to tap BOTH in and out. One could tap outwards
> one
> > turn too many and then begin to tap outwards from the inner turn to get
> > the inductance just right.
> 
> > So much experimenting still to do!
> 
> > Thanks again, Gary, for sharing your experiments with us!
> 
> > Fr. Tom McGahee
>   >>
> 
> Fr. Tom,
> 
> Wise comments as usual.  Have to try to tease out those universal
> principles.
> Your suggestion of tapping in, or in and out, could also be used to keep
> the
> coupling factor more constant without having to vary the pri to sec
> height
> relationship.  In some cases, tapping "in" may lead to primary to
> secondary
> arc-overs due to the autotransformer action of the unused inner turns.
> 
> I agree that the unshared data of one's work can often provide
> invaluable
> clues when viewed from another's vantage point.
> 
> So much experimenting to do.....I second that viewpoint.    :)
> 
> John Freau


I did some experementing with tapping the primary coil from the inside
out 
but not much.  I found there small difference by tapping past the 1st
inside 
turn but a bigger difference at the 2nd turn and several times more 
difference at the 3rd turn. Its a non linear change. I think maybe
coupling 
was dropping off fast by tapping away from the secondary coil because
the 
secondary coil output sparks dropped off very fast.  When I noticed this
I 
decided not to experement with this any more.  Hum...........this might
be 
another method of adjusting coupling.

I had an idea of building a primary coil mounted in rollers.  100's of
tiny 
ceramic or plastic rollers every few inches the entire length of the
primary 
coil.  If coupling needs to be changed the entire coil can be rotated
clock 
wise or counter clock wise to make the primary coil larger or smaller
and the 
turn to turn spacing will stay the same.  The inside turn of the primary 
could then be adjusted closer or further away from the secondary coil. 
If a 
larger cap, toroid or power supply is used the primary can be roatated
to 
adjust coupling and prevent arc over.  A primary coil of this type would 
involve many hours of work.  Would it be worth it?  


Gary Weaver