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Re: 2 layer primary puzzle



Original poster: "David Wilson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <david-at-computan.on.ca>

Hi James ,
  The direction of the winding is important, if the first layer is CW and
the 2nd layer is CCW
then you have a precision resistor with no inductance.

cheers David

Tesla list wrote:

> Original poster: "James T by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jamest2000-at-att-dot-net>
>
> Hi Everyone,
>  I will keep this brief. I am working on an 8" coil with a 2 layer primary.
> I have constructed the primary and
> it is not behaving as I expected. I measured the inductance of the primary
> by itself.
>   What happens is, I measure from the outside of the top coil to the inside
> and the inductance goes up as
> expected. Then I drop down to the bottom layer and measure from the
> top/outside to the bottom/turn, oops, the
> inductance goes down as I go out. The inductance of the bottom coil seems
> to cancel the inductance of the top
> coil. Please set me straight on this.
> 1.understanding/myth - the winding direction between the 2 coils is
irrelevant.
> 2. understanding/myth - the "mutual inductance" of the 2 coils increases
> inductance, not cancels out the
> others inductance.
> 3. 2 layer primary's are a practical approach. I seem to recall some posts
> on this, and it was considered
> reasonable. Brilliant to ask now that it is done!
> Any comments will help. Thanks,
>  James Cart