Re: Best Primary Coil

To: tesla-at-poodle.pupman-dot-com
Subject: Re: Best Primary Coil
From: Tesla List <tesla-at-stic-dot-net>
Date: Mon, 28 Apr 1997 00:21:46 -0500
Approved: tesla-at-stic-dot-net
Subject:       Re: Best Primary Coil
       Date:   Sun, 27 Apr 1997 20:10:00 -0700
       From:   Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization:  Greiner, Ltd.
         To:   Tesla List <tesla-at-pupman-dot-com>
 References: 
            1


Tesla List wrote:
> 
> 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

Gary, John and all

I use solenoid or cylindrical primaries. As a matter of course I have
always tapped from both ends to adjust both coupling and L. It does work
very well. 

Skip