# Re: Primary Coil (and cap?) INSIDE Secondary Coil

```OK, now the gauntlet has been thrown down . . . the challenge is stated:
Can a cap be made to be a primary inductor?

The first thought is inevitably: " but what about the current which is the
source
of the
magnetic field? how do you create a right hand current in a cap? and not
just  on 1
side but on both sides of the cap."

Option 1:
How about a filiary (wire) cap with the two connectors on opposite ends?
wrap the
cap wire helically, Could you generate enough current in the two wires
during the
cap charging/discharging to create a decent B field? Yes, if the wires
discharge in
phase. The current should be the same as for an equivalent µf cap and length
inductor, should it not?

Option 2:
For plate caps the net E field vector during dishcharge has to be along the
axis
from it's geometric center to the point through which it is discharged.
Extrapolationg this to the topological equivalent in a rolled cap dictates
that in
order for the spiral discharge vector of the two cap plates to not be
anti-parallel
in current direction one of the plates has to be connected at the perifery
of the
roll and one at the center. If the connectors are placed at the opposite
ends of
the roll as well as at center and edge; the discharge net vectors are
helical and
co-linear and parallel. The field generated would be the equivalent of a wire
carrying the current of the caps discharge along the conical helical path
between
the connectors, with N = the number of spirals in the cap.

Zie gedankenexperiment  ist koenig.

Bryan Kaufman

> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>
>         I had this thought the other day.  Since capacitiors are usually
rolled.
> Would it be possible to use a capacitor as both the primary capacitor and
> primary inductor in one unit?  In other words, the spiral plates of the cap
> would also serve as a spiral primary inductor?  Or, would the fields always
> canecl the effect??  such a unit would be really neat for the situations
> where you would insert the primary inside the secondary.
>
> My gut feel is that the physics would not allow such a machine to work,
> but....
>
>         Terry

```