Re: 1500-3000 turn coils

["Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:
 
> Original poster: "Dan Kunkel" <dankunkel-at-hotmail-dot-com>

> how does one go about finding out these "magical" values? by geometry do you
> mean conical, flat wound or helical shape only? or does it also incorporate
> primary wire gauge and turn to turn spacing?

The "magical values" for the coupling coefficients are all the values
obtained from the expression:
k=(b^2-a^2)/(b^2+a^2) 
where "^2" means squaring and a and b are two integers with odd
difference.
Ex:
a=1, b=2: k=3/5=0.6
a=2, b=3: k=5/13=0.384
a=3, b=4: k=7/25=0.0.28
It's also possible to use differeces of 3, 5, etc.
This relation comes from conditions applied to a lossless Tesla
transformer, forcing the existence of a time where all the energy
that was originally in the primary capacitor is in the secondary
capacitance. You can see more about this in:
http://www.coe.ufrj.br/~acmq/tesla/magnifier.html
See the simplifications in the magnifier design equations that result
in the conventional Tesla transformer.

The coupling coefficient essentially measures how much of the magnetic
field generated by one coil crosses the area enclosed by the turns of
the other coil (if both coils were thin toroids, k would be exactly
this). It depends essentially in the shapes and relative positions
of the coils, and not on how many turns they have (double the number of
turns, keeping the same overall shapes, and k is the same) or on 
wire gauges (practically no relation at all). How the turns of the coils
are distributed along the coils affects k. Two primaries with same
number of turns, same shape, but with turns more concentrated on
different ends would result in different ks with the same secondary.

Antonio Carlos M. de Queiroz