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

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
> 
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

> 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.

Two closely coupled inductors connected in parallel have the same
inductance of a single one. It's equivalent to make the inductor with
a wire with doubled area.
 
> 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.

Ok, but with single loops the inductance of the connecting wires makes
significant effect too.
 
> Theoretically.  I could get a tuning range of 1/2 to 4 X that of a single
> loop in this way.

1/2 to 1, ideally.
 
Antonio Carlos M. de Queiroz