Re: Hello everyone

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

>
> I do have a question to ask... If we go with the slinky metaphor put
forward
> by a few sights.. When you get the slinky strong enough to break the wall,
I
> am assuming the slinky is under great stress at this point.. And being
> slightly out of time with your forces (mistuned) you could do some nasty
> damage to the slinky.. Correct?  And i would also assume that because
there
> is loss in the system (the friction of the slinky on the floor) that there
> is of course a theoretical maximum force the slinky can reach..
>
> What i'm really asking, is there a decent resource describing the entire
TC
> model for simulation?  Are we still faced with unknowns or can the
> engineering of ones TC be completly modelled in software before
production?

I would say that the electrical aspects of the inductances and capacitances
can be very well modelled. Terry has a bunch of pSpice models for lumped
models, Antonio has differential equations for just about everything, and
Paul has numerical and analytical models to address all the subtle details
of proximity effects, winding inductances, etc.

 The tough to model aspects are:
1) spark gap behavior
2) The effect of the sparks coming off the top load.  They are dynamic, have
inductance, capacitance, and resistance that changes (rapidly) as a function
of time, and have a significant effect on the overall system.

The other aspect is that you may be able to model to a thousand decimal
places, but I doubt your construction tolerances are that tight.  In
general, 5-10% is reasonably achievable, and if you model and build to that
accuracy, your model and your actual item will probably match.  If you are
worried about the variation due to presence or absence of dust on the
topload, then you're going to have to find a way to describe the dust with
sufficient fidelity, etc.

And, given that there is a large degree of empiricism in all these things,
one shouldn't neglect the work of folks like John Coture, who took
"zillions" of measurements on various sizes and shapes of coils and turned
them into useful programs that can generate very nice designs, without
necessarily going to the last decimal point on mutual inductance.

My only caution to you is to avoid "analysis paralysis"... Get some parts,
get one of the spreadsheets or programs, and start building your first coil.
Once you get 2" or 3" sparks..(i.e. any sparks), then start to obssess about
optimizing and performance.  To a large degree tesla coil building is as
much about mechanical craftsmanship than electrical performance.  All those
horrible practical details can only be answered by first hand experience:
how to wind hundreds of turns on a secondary tube (be it cardboard, PVC, or
whatever) and keep them there without it turning into a rat's nest of
overlapped and kinked wire.  How to hook the HV transformer to the spark
gap, etc.    Fortunately, you probably can avoid the delightful exercise of
rolling capacitors from polyethylene sheeting and aluminum flashing... It's
cheaper to go with the newer multiple mini capacitor (MMC) route, and
infinitely more reliable.  For the truly low cost approach, glass bottles in
salt water is about as low buck as you can get. Heavy, Messy, Mediocre
performance, requires maintenance but it works, and is almost free.