Re: Theoretical understanding

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

Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Tristan,

On 8 Dec 2003, at 8:10, Tesla list wrote:

 > Original poster: tristan Matthews <thrawnda-at-yahoo-dot-com>
 >
 >
 > I would like to start by thank every one for there help so far. But
 > there are two critical things that I still don't understand.
 >
 > First of all on Richie Burnett web site, which btw was very help full,
 > he talks about notches in the primary and secondary voltages wave
 > forms where all of the energy is transferred from one to the other. In
 > my mind it seems that as a current is induced in the secondary by the
 > primary it would then begin trying to induce a current back in the
 > primary. So that it would be losing energy at the same time that it
 > was gaining it. There would still be a periodic nature to the transfer
 > because the transfer rates will still be dependent on the resonant
 > frequencies. But instead of all of the energy flowing from one to the
 > other it would reach a equilibrium where the current in the primary
 > was trying to transfer energy to the secondary at the same rate that
 > the current in t! he secondary is trying to transfer it back. (It is
 > very possible that I simply don't understand the nature of problem
 > properly in which case simply tell me it doesn't work that way and I
 > will go work through the math and see what happens.)<?xml:namespace
 > prefix = o ns = "urn:schemas-microsoft-com:office:office" />

In short, energy trades are periodic but unless the coupling constant
is set to one of a set of certain values, the trades may not go to
completion before switching sides. The "certain values" often quoted
are for the lossless cases which doesn't quite apply to real world
coils so allowances have to be made. Best done by observing the
trades on an oscilloscope at low power and adjusting the coupling.
Once the sparks start flying, all bets are off (but that's OK because
that is what we want ;)

 > Second I simply don't see how the secondary can behave as a LC circuit
 > in that it is grounded at the bottom and it clearly has enough voltage
 > at the top to ionize the air and discharge that way. So how is it that
 > it can resonate with out extreme damping from the top discharge and
 > the voltage simply flowing away in to the earth when the peek voltage
 > flows to the bottom?

In practice, air streamers cause the unloaded Q of the secondary to
drop by 50% or so according to measurement. Sparks attached to
another object cause it drop substantially more and strong attachment
can reduce energy trades to just a single pri-sec transfer. Again,
you can see this on the scope. Attached sparks are loud and bright,
also an indicator of power dissipation. Additionally, the primary gap
dims substantially for a well coupling-adjusted coil run under this
condition, further indicating reduced dissipation in the primary
circuit.

Malcolm

 >
 >
 > Thanks for your time
 >
 > Tristan Matthews
 >
 >
 >
 > p.s. please forgive my lack of spelling and proper grammar.
 >
 >
 > Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Dr. Resonance"
 >
 >
 > Richie Burnett's site from England has clear explanations how the TC
 > operates.
 >
 >
 > Dr. Resonance
 >
 >  > >
 >  > > Hi everyone, i have just joined the list after finishing building
 >  my
 > first
 >  > > Tesla coil as a UCB lab class final project. While I was been
 >  able to
 > find
 >  > > an amazing amount of information on the web about how to build
 >  the
 > coil,
 >  > > but was unable to find any really understanding of how it
 >  theoretically > > works. The book "Modern Tesla Coil Design and
 >  Theory" by Duane A.
 > Bylund
 >  > is
 >  > > most commonly, and almost exclusively, referenced but it has gone
 >  out
 > of
 >  > > print and I have been unable to find a copy of it. So I'm I find
 >  my
 > self
 >  > in
 >  > > search of guidance as to what reference! s others have found
 >  useful?
 >
 >
 >