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Re: Flat Coils



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

Excellent point...  If you have a series of turns: 1,2,3,4,5,6,7,8  and you
are analyzing turn #4, for example, it's coupled a lot more to turn 3 and 5
than to turn 2 and 6, etc...

In the limit, with a donut shaped coil with large overall diameter, and the
windings all clumped together in a line, either axial or radial, the
inductance will be the same.

Especially for a secondary, which has a LOT of turns, the difference in
diameter/spacing (and hence coupling) between adjacent turns for the two
configurations (helical vs flat) is going to be smaller than for a primary,
which is typically space wound.

And, of course, conical primaries/coils, will be somewhere in between.

You know, if you just put a magnetic core in the middle, then all these
issues about coil shape become almost moot.  The flux from the core will
dominate.


Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Dwight.Crider-at-regulusgroup-dot-com>
> 
> FWIW-It seems that the flat and solenoid coils would approach identical
> values as the physical sizes get larger in proportion to the current -field
> intensity. ( The fields are interacting with the same numbers of turns in
> both cases) When the sizes are smaller in proportion to the same field
> intensity, it seems that more turns are mutually affected because the flat
> spiral's inner turns are physically closer at the center. (Assuming in all
> cases the field intensity per turn is constant) Just a thought,  I :o)
> 
> Dwight Crider