# Re: Couples Therapy

```Hi Antonio, all,

> Original Poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
>
> Tesla List wrote:
> >
> > Original Poster: "Ruud de Graaf" <rdegraaf-at-daxis.nl>
>
> > Sorry, but I don't understand your formula (and I can imagine there are
more
>
> The complete derivation is a rather long story. I will make it available
> in the web soon by a new method that I have found. That formula is what
> results from a magnifier design if you remove the secondary capacitor
> and consider the resulting circuit as a Tesla coil.
> (see http://www.coe.ufrj.br/~acmq/tesla/magnifier.html)
<snip>

> > Overcoupling is the moment that an inductive loose coupled bandpass filter
> > stops to decrease the weakening of the signal transfer and the bandpass is
> > widened to form two peaks in the dB/f graph. This is on a distinct point in
> > the graph. k<k-critical -> 1 freq-peak (fo),
> > k > k-critical -> two freq. peaks period. What exactly do YOU mean with
> > overcoupling.
>
> This condition would require explicit resistances in the circuit, and
> result in an extremely lossy Tesla coil.
> Tesla transformers are designed to operate as essentially lossless
> circuits during the energy transfer. In this sense, they are always
> extremely "overcoupled", using that definition. I don't see any
> relation between the theory of coupled bandpass filters and Tesla
> transformers. The circuits are similar, but the function is different.
> The most usual reference to "overcoupling" that I see in this list
> is in the sense that the transformer has its windings excessively
> close. This can only create arcing. There is no limit in the coupling
> coefficient of an efficient resonant transformer, other than 1,
> and no relation to the meaning of the term "overcoupling" in filters.
> As Malcolm said, sparking coil (induction, or Ruhmkorff coils) operate
> with tight coupling coefficients and work well too.

Unfortunately I was referring to "ordinary" TCs that were emitting
sparks. I hereby confess to using the term "overcoupling" in its
classical sense. There are any number of reasons why I do this but
here are a few:

- the definition is a stricture with regard to frequency response.
- the Corums use it exactly the same way (before I get jumped on
for that let me just say that in their texts they claim that those who
don't use special fast quenching gaps are forced to operate at or
near "critical coupling").  Again, "critical coupling" is strictly defined.
(BTW - I think that claim is utter nonsense - by the time you get
unloaded high Q coils to couple critically, they are several feet
apart).
- overcoupling as used by some to describe the condition whereby
racing sparks occur is ill-defined. For a start, there is no valid
evidence to show at which k exactly racing sparks occur - as we all
know, it varies from coil to coil.

Regards,
Malcolm

```