RE: Coil Design

            RE: Coil Design
            Tue, 15 Apr 1997 17:18:14 +1200
            "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz>
            Wellington Polytechnic, NZ

Hello all,
             John asked....

> >> Interesting article.  I don't understand the sentence:
> >> "This {mutual inductance} can be reduced or eliminated
> >> by proper geometry where the loops overlap each other
> >> such that the net mutual inductance is zero".
> >
> >A similar thing is done for induction-balance metal detectors. It 
> >simply means the coils are positioned in such a way that coupling 
> >between them is reduced to near zero (there's one for the critical 
> >coupling enthusiasts :)  There was a short article in Electronics 
> >Australia a year or two back which showed the method invented to 
> >eliminate coupling between air-cored coils in early radio sets where 
> >the coils were mounted in a line but at around 40 degrees or so lean 
> >from vertical, all leaning in the same direction.
> >
> >Malcolm
> >
> > ----------------------------------------------
>   Malcolm, all -
> I haven't seen the article but have some questions. Are you saying
> that the mutual inductance can be "reduced or eliminated" for Tesla
> coils? What would be the advantage?

None at all. Perhaps it was off-topic.

>  It is obvious that it is a simple matter to reduce the mutual
> inductance by proper geometry as Benson stated. I once used this 
> idea for a homemade regenerative receiver. But I don't believe this 
> is of much value for Tesla coils.

Fair comment except that I think anything relating to coupling/tuned 
circuit behaviour is of interest.
>  However, you said there were other design issues pertinent to Tesla
> coils.
> Can you elaborate for the benefit of the Tesla List?

Once again, the article discusses issues related to coupling, 
impedance matching etc. I couldn't do justice to the article by 
attempting to paraphrase it. If you are interested I suggest getting 
a copy.
     I have a post coming up in answer to John Freau about Z matching
in 1/4 wave transmission lines in a day or two.