Re: Desktop Bipolar Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:
 >
 > Original poster: "Stephen Conner by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

 > >I've seen many bipolar coils many of which have overcoupling on both
 > >secondarys which will result in a shorter spark length than optimum
 > >performance would
 >
 > Can overcoupling really make performance fall off? In my own (limited)
 > experience I've only ever found that the tighter the coupling the better it
 > works.

The most that can happen is a very slight drop in performance if the
coupling coefficient happens to be between two of the optimum values.
But this is only observable without instruments when the coupling
coefficient is above 0.28 or so. There is a significant dip between
0.6 and 0.38 and another smaller between 0.38 and 0.28. But usual
Tesla coils operate with significantly lower coupling, and in that
range what dominates is the smaller losses that result from higher
coupling. There is nothing that can be called "overcoupling" in a
normal Tesla coil. This term is used in doubly tuned bandpass filters,
and is characterized by a frequency response with two peaks instead
of just one (the also so called "frequency splitting").
But these filters are far more lossy than the worst of Tesla coils,
that are always very deep in the "overcoupled" region, and so
the quoted terms above, in their normal sense, don't apply.

Antonio Carlos M. de Queiroz