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Re: Flat coils & undamped waves

Original poster: "Gary Peterson" <g.peterson@xxxxxxxxxxxx>

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Why is flat coil geometry significant in this . . . context?

There doesn't seem to be anything special about the flat spiral secondary within the context of generating undamped waves. The flat-spiral resonator was used early on in Tesla's wireless transmission research, and although he hung on to the thing, it can be seen from later patents and other sources that, for transmitters at least, the design was largely replaced by single-layer helically wound coils.

In speaking about the C/S magnifying transmitter Tesla said,

    ". . . [the production of] a circuit which would give me,
with very few fundamental impulses, a perfectly contin-
uous wave . . . came with the perfection of the devices.
When I came to my experiments in Colorado, I could
take my apparatus like that and get a continuous or
undamped wave, almost without exception, between
individual discharges."

In other words, by configuring a disruptive discharge Tesla coil RF transmitter in a way that production of electromagnetic radiation or "radio waves" is minimized, then the damping factor is made small and the amplitude diminishes only slightly between primary impulses. Because of this Tesla felt comfortable characterizing the wave form as being undamped, "almost without exception."

Perhaps I'm not understanding something correctly . . .

Yes, I suggest that you go back and look at the excerpts once again.

. . .Vacuum tube Tesla coils and some non-disruptive solid-state coils do generate CW, or undamped waves, but Tesla lacked the technology to do this using active devices.

Better yet, go ask your local librarian to obtain the book NIKOLA TESLA ON HIS WORK WITH ALTERNATING CURRENTS AND THEIR APPLICATION TO WIRELESS TELEGRAPHY, TELEPHONY, AND TRANSMISSION OF POWER : AN EXTENDED INTERVIEW, Leland I. Anderson, editor, Twenty First Century Books, 2002, for you through Intra Library Loan (ILL)and then read through it a few times.

Did he couple a mechanical high frequency alternator into a matching resonant transformer, to boost the voltage
and produce a true CW Tesla coil?  Was resonant-rise involved?

Yes, keeping in mind that the perfected alternator had, "a certain small number of [widely spaced] poles," that was rotated at, "an enormous speed," and generated, "sudden impulses which would produce the same effect as the [primary] arc discharge in [the] so called "Tesla transformer."" In addition to the alternator there was an associated mechanism assuring the AC power supply's output was precisely constant in frequency. You may be aware of Tesla's U.S. Patent "Electric Generator," No. 511,916, Jan. 2 1894 for the production of isochronous oscillations. Furthermore, he could convert the AC to DC,

   ". . . This dynamo, you see, is a two-phase machine;
that is, I develop from it currents of two-phase.  Now,
there are four transformers, you see them down here,
that furnish the primary energy.  From these two phases
I develop four phases.  This involves something else
which I have referred to before; namely, an arrangement
which enables me to produce from these alternating
currents direct currents and undamped -- absolutely
undamped -- isochronous oscillations. . . ." [p. 64]

In other words, he could charge the primary condenser bank using direct current, and then discharge it using a high-speed rotary break and in that way produce, "absolutely undamped waves."

    "The arrangement was simply this.  I had a number
of studs with cups which were insulated, 24 if I recollect
rightly.  In the interior was a mechanism that lifted the
mercury, threw it into these cups, and from these studs
there were thus 24 little streamlets of mercury going out.
In the meantime, the same motor drove a system with 25
contact points, so that for each revolution I got a product
of 24 times 25 impulses, and when I passed these im-
pulses through a primary, and excited with it a secondary,
I got in the latter complete waves of that frequency. . . .
I would get . . .  60,000 primary impulses, and in the
secondary a frequency of 60,000 complete cycles.  The
primary impulses were unidirectional.  They came from
the direct current source, but in the secondary they were
alternating -- full waves. . . . They were entirely persistent.
I had 60,000 per second absolutely undamped waves;
they could not be damped." [pp. 77-80]

. . .  Perhaps vagueness was his intent?

Gary Lau

I can appreciate that Tesla's thoughts might be difficult to grasp with his words ripped out of context as I have done. I'm certain that he was doing his very best to be clear.