Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com>
Here are some very helpful responses I received from Richard Hull in the
past few weeks. Richard Hull has built hundreds
of tesla coils as well as spent many years designing, testing, and
refining magnifiers. I would also strongly recommend his two Magnifier
Videos: Magnifier I and Magnifier II. Both videos are $25.00 each
(includes shipping) and are two hours
in length each for a total of 4 hours of magnifier video!
-Dan
(Responses below from Richard Hull)
REGARDING PRIMARY TO SECONDARY COUPLING AND SPACING
I ran mine real close and insulated the secondary driver coil from the
primary with a large seven or eight layer wrap of polyehtylene sheeting
about 30 mils thick. With 20kv on the primary I used about 4" spacing
off 16" secondary for magnifier 11E.
REGARDING FREQUENCY OF SECONDARY COIL AND RESONATOR COIL
The resonant frequency of the secondary or the extra coil turn out to be
pretty unimportant! The key is to make the driver secondary very
tightly coupled and have only about 100-200 turns of heavy gauge wire on
a form more or less 6-10 times the diameter of the resonator or extra
coil. The resonator/extra coil must have a lot more inductance than the
driver or, barring that at least a natural resonant frequency of half
that of the driver secondary. The resonator must be toploaded to beyond
apparent reason and near to insanity. A four inch diameter extra coil
should have at least a 50"X8" toroidal terminal. Part of the art is in
fashioning this terminal system. Even though the terminal of most tesla
systems is a high impedance point, the magnifier must be so grossly top
loaded that the output impedance is very low. This means an arcing Q
that is ridiculously low. The primary is tuned for whatever makes the
largest spark. It is important that no visible corona exist on the
transmission line. This means a giant diameter line. 1" copper pipe
minimum. The key is to deliver large amounts of RF current into the
extra coil's base.
No magnifier can be designed by radio theory. Only efficient RF
communications systems can be designed by radio theory. The magnifier
is a study in supplying the maximum amount of RF energy to a massive
capacitive terminal and maximizing the RF losses via electrical break
down into a GAS LOAD at STP (standard temperature and pressure)....the
atmosphere.
The rotary break must be capable of supplying pulsed RF energy to this
gas load in a unit time shorter than the bulk deionization or relaxation
time of the arc channel. In this fashion the load is kept dynamic and
at each new energy pulse delivery, the RF energy travels out further on
the ionized path of the last pulse before the channel cools (deionizes).
This allows the channel to not only be renewed, but slowly grow or
extend out farther with each pulse and if it attaches to a grounded or
near ground object, the arc channel will stay connected for seconds at a
time. The mystery is what breaks the channel, ultimately.
A tesla coil or a magnifier is not a refined RF machine, it is a gas
load matched ionization system. (as built by the amateur) In the end,
after ten years and hundreds of coils large and small, I stopped
calculating as I became as Tesla said, 'able to see in my mind's eye and
craft with my hand that which was proportionate and functional', not
through anyhting so elegant as equations or as silly as mysticism, but
by constant application and the doing. A synergy moves into the breast
that assists the adroit and adept at the work. What works often flys in
the face of reason. It took ten years for me to realize that the art of
tesla coiling and making big sparks was not in the coil, but in
understanding the ionization of gases and how to match electrical
systems to this strange, dynamic load.
Look at how our stuff evolved over the tapes and you will get the idea.
every magnifier got smaller and produced similar results with less
energy (in most cases). The culmination was in magnifier 11E (only seen
on the later report tapes.) >10 feet of hot spark out of a 4" diameter X
13" long resonator wound with #30 wire. Part of the success was our
design and discovery of the series quench rotary back in 1994 allowing
proper quenching at tunable break rates. Ed hopped on the design the
momnent he saw how effective it was for our magnifiers and the benefit
it gave his own fledgling system back in 96-97. He never worked the
tiny resonators, to the 10:1 spark to coil length ratios, though, like
we did. Tesla never even achieved this goal, but his stuff was made
with the crappy materials of his time. We used the best insulation and
90 years of advancement in material science he didn't have.
(Above responses from Richard Hull, TCBOR)
> Hello Coilers,
>
> As a winter project I'm going to tackle building a small
> magnifier type
> of Tesla coil. I have a hard time with math and complex
> formulas, so I
> want some "laymans" advice on a few aspects of magnifier construction.
>
> Here's what I do know: 1) The "extra coil" can have a high inductance
> and a larger than normal top load. 2) The secondary is
> tightly coupled
> to the primary, which is in the helical form rather than a
> flat spiral.
> 3) The secondary is not resonant, but rather works more like a step up
> transformer, mainly due to the high coupling.
>
> Now the questions: 1) Is the primary's resonant frequency the same as
> that of the "extra coil's"? {I suspect that it is} 2) Is
> there a rough
> ballpark figure as to the turns ratio between the primary and
> secondary
> of the driver? 3) How much does the secondary effect the frequency of
> the "extra coil", as I would think it would lower it to some degree?
>
> I've gleaned most of what I know on magnifiers from Hull's
> guide to the
> CSN and from searching the list's database, but I'm still in the dark.
> Any and all advice would be appreciated, but please keep the math to a
> minimum. By the way, I use WinTesla to calculate the ballpark figures
> for the "extra coil" and topload, as well as the primary.
>
> 73, Weazle, VE3EAR/VE3WZL
>
> Details of my "Hyperbaric Gap" and Tesla coil are at:
> http://www.hurontel.on.ca/~weazle
>
>
>