Re: Extra coil

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

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

Tesla list wrote:
 
> Original poster: "Nebojsa Kovacevic by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <morfeus-at-EUnet.yu>

> Most of the people are confused with the part of the Tesla coil which he
> named "extra coil". 

As John Freau already said, this is a "magnifier". A device that is
commonly used in high-energy pulsed systems, and that is a higher-order
version of a Tesla coil with some interesting properties.

> This type of coil is now
> days known as opened helicoidal resonator.

Ok. But a lumped LC model works quite well for it.

> The configuration we are comonly using today is producing high voltage
> only (high energy). But if we want to get high voltage and high
> amperage, we should construct the system with tertiary coil.

No. There is no energy gain at all. Better efficiency with proper
construction, maybe.

> Let`s take a look at the Tesla`s apparatus as a perfect example. He used
> adjusted main oscillator for transform low frequency to radio frequency
> currents. Primary coil has very high inductive relation with the
> secondary, which has the serial resonance of the same frequency as
> adjusted helicoidal resonator from which Tesla emitts his streamers.

Humm...

> Many people are surprised that the secondary coil is adjusted on the
> exact frequency as the primary coil. The real attention should be paid
> on the extra coil which spectaculary dominating on the central part of
> his lab.
> Rotary break is the most important part in the constuctions with extra
> coil. 

No special reason for this.

> Before all, for a high power you need as many breaks as you can
> acchieve per second. 

True, as a magnifier can be designed for very fast energy transfer.

> Everyone has to have in mind that high amperage in
> the coil doesn`t mean very high voltage. The power which is transmitted
> to the secondary coil is proportional to the number of the breaks in
> second. Other usefull aspect of the break is the break duration which is
> the key for a proper functioning of the primary and secondary coil. The
> time duration of the spark in the break is the time in which the spark
> really exists in the gap before it shuts down.
> While the spark is in the gap, the system will oscillate on the two
> frequencies (two line system so to call it). Spectral diference, or the
> frequency diference is proportional to the magnetic relation between the
> primary and the secondary circuits. To get the max. results, these two
> frequencies should have the frequency diference DF.

There are optimal DFs, and an optimally designed magnifier has -three-
oscillation frequencies, not two.

> All this means that with incresing the inductive relation between the
> primary and the secondary, the time of the spark in the gap should be as
> shorter as possible. But, in the case of critical relation between the
> coils, DF is falling to zero, so the duration of the spark isn`t a
> controll parameter any more.

Wrong. Fast energy transfer -maximizes- the frequency differences.
 
> The readers familiar with the problem must ask them selfs, why to build
> an extra coil? Isn`t the finall goal we are all trying to acchieve,
> generating a high potencial (energy)? This is true if we want to get
> only high potencial. Hmm....our friend Tesla must have wanted more. In
> Colorado, he wanted to get  high potencial and very high power.

Humm...

> We are all aware of the two frequencies that builds in the system with
> very high inductive related coils(primary and secondary). The phenomenon
> of two frequencies. This can be seen as a two frequency spectre on the
> o-scopes with primary and secondary coils with concentrated parameters.
> Extra coil should be noted as a diferent part of the system, comparing
> to the one we have in the primary-secondary system. (When it is compared
> with the secondary coil, it`smagnetic relation to the primary coil is
> minor). Extra coil is infact 1/4 wave lenght helicoidal resonator.

So far, ok.

> Analise of the tertiary coil as a concentrated parameter circuitry is
> absolutly unsuccessful.

Wrong. The analysis is somewhat more complex than in the double coil
case, but the results are easy to obtain and verify. If there is
some discrepancy between predictions with a lumped model and actual
behavior, it's due to the distributed nature of the resonator,
but a conventional Tesla coil uses an identical resonator, and shows
similar discrepancies too. Small.

> In every way, the looses should be cut down in the tertiary coil.

As in the secondary of a Tesla coil.

> Helicoidal resonator on lower frequencies is only a coil of the small
> diameter with high number of turns of wire, placed above the ground.
> Coil, with capacitor on the top acts as a 1/4 wave lenght "antenna"
> which doesn`t emitts. Instead of the vertical tower a few thousands of
> feets high - real aerial, Tesla had the resonating coil which doesn`t
> emitts, and it`s hight was only a part of that hipotetic tower. The
> nature of the slow waves in the coil is what makes all this possible. It
> should be paid attention on a few things about the helicoidal
> resonators:
> The base or entry will have the characteristical low impendance, and on
> the top (or the high frequency exit), will have high impendance. This
> means that in the purpose of the activating the coil Tesla had to
> connect a very high currents to the base of the extra coil. That way, as
> much electricity you put in the base of the extra coil, with  properly
> adjusted frequency, the more electricity you will get on the top of the
> coil(terminal). The currents on the top depends on the high frequency
> currents in the base of the extra coil, short wave voltage ratio, and
> the characteristical impendance of the resonator. All these claims can
> be measured and calculated very easily. 

No. The operation is transient, and there are three frequencies
(or two in a Tesla coil) involved. Impedance concepts can't be 
applied so easily, and are not very useful here.

> Besides, as tertiary coil can be
> used any 1/4 wave lenght resonator which doesn`t emitts - helicoidal
> resonator, coaxial resonator, even microwave owen!

Makes sense, but a microwave oven?

> I am hoping that in this point, every reader is abble to see that the
> combination of the primary and the secondary coils is, efectivly, only
> one powerful oscillator of the high energy, which brings the currents of
> the low voltage and high amperage in the base of the extra coil, in
> order to build a high potencial high energy currents.

This is not so for a capacitor-discharge system. The "oscillator" 
operates at more than one frequency, and turns off when the energy 
is completely transferred.

Look how a magnifier can be treated and designed exactly with lumped 
parameters:
http://www.coe.ufrj.br/~acmq/tesla/magnifier.html

Antonio Carlos M. de Queiroz