Re: Variable Mutual Inductance Primary Tuning (VMIPT Sorry :o)))

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



Tesla l
> There will be two primary coils (actually two BIG single turn loops of
> copper).  They will be movable so that the two loops are either very close
> together or maybe up to 6 inches away from each other.  They will be wired
> in parallel.
> 
> When they are close together, they will have high mutual inductance between
> each other so the "total" inductance will tend to increase.  If one roughly
> assumes the inductance is proportional to N^2, I would get about 4X the
> inductance of a single loop when they are close together.
> 
> Now if I move them apart so the mutual inductance is low, they will tend to
> act as two magnetically separate inductors wired in parallel and the
> inductance will be roughly 1/2 that of a single loop.
> 

N^2 only if turns are in series... consider a limiting case where the two
coils are on top of each other, connected in parallel.  It's electrically
and magnetically just one turn. 

You'll have to get them pretty far apart to make the coupling low enough
that the inductance is halved.