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Re: Flat coils & undamped waves (was Wire Length)



Original poster: "Kurt Schraner" <k.schraner@xxxxxxxxxxx>

Tesla list wrote:
Original poster: "David Thomson" <dwt@xxxxxxxxxxxx>
<big snip>

http://www.tesla-coil-builder.com/FlatSpiralSolenoidCombo.htm

When it comes to winding flat spirals with ribbon wire, there is no
advantage from the extra self-capacitance because the flat wire acts
like several coils wound in parallel, thus the inductance is decreased
accordingly.  Calculating the frequency of the flat spiral using the
Wheeler inductance formula for flat spirals made from round wire
works the same for flat spirals made from ribbon wire.

Dave

Maybe I'm splitting hairs, but I have to disagree about the last sentence, of Wheeler formula application for ribbon wire flat spirals. Please see my 2004 TCML posting:

http://www.pupman.com/listarchives/2004/October/msg00018.html

especially the 2 graphs:
http://home.tiscalinet.ch/m.schraner/Lstrip_Wheeler.gif
http://home.tiscalinet.ch/m.schraner/Lstrip_NBS.gif

To use the right calculation method can be crucial, when designing a ribbon type flat spiral primary: the too high L prediction of Wheeler may lead to a too small primary construction.

Kurt