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Re: Now, How does a coil really work??
Tesla List wrote:
>
> Original Poster: RWB355-at-aol-dot-com
>
> Hello all,
>
> After reading some of the comments on my post about a TC coil not
experiencing
> resonant rise (spark length increase is due to the resonant rise), I have
> become more confused than ever.
>
> I will believe that the primary circuit experiences LC resonance (that is
what
> we want, if I understand it correctly) and that this will increase the
amount
> of energy available in the primary in comparison to a single shot from
the cap
> to the primary coil w/o resonance (i.e: a simple discharge of a charged cap
> into a certain coil with little or no LC resonance occuring).
>
> I will also believe that in order to transfer as much energy as possible you
> will want the secondary to resonate at the same FRes as the primary.
So far, so good.
>
> However, the way I understand resonant rise (maybe this is incorrect ??) is
> that the output energy of the coil will be greater than what you "stuff"
into
> the primary. This would violate the energy conservation laws and I donīt see
> how this is possible.
Not quite. Resonant rise in the case of a TC means that I'm increasing
the amount of energy stored in an oscillating LC circuit by the properly
timed tranmsfer of energy from an external source [the primary LC
curcuit]. After I've repeated this energy transfer process a number of
times, the resulting energy stored in the oscillating LC circuit can be
many times greater than the amount of energy I've transferred on each
"push". However, because of losses, the amount of energy stored in the
secondary LC system will always be LESS than the total energy I've put
into the system from the primary (i.e., I agree with your Conservation
of Energy argument).
I'd contend that, during the transfer of EM energy from the primary to
the secondary, I am seeing resonant rise, since the energy in the
secondary is being "accumulated" in the process. The key is: While my
primary energy is decreasing, my secondary energy is increasing - this
phenomena can only be explained through the mechanism of resonant rise,
and is fundamentally attributable to the relatively high Q of the
oscillating secondary system (prior to breakout).
>
> I can not see how you can store a charge on the coil (alone). The toroid
is a
> totally different matter. Cself is so small, that it canīt hold any kind of
> reasonable charge for a length of time. The toroid, on the other hand, is
able
> to do so. The bigger the toroid, the greater the voltage is, that can be
> stored on it (i.e. longer sparks) before breakout will occur. This, of
course,
> has limits. If your toroid is so big that a breakout canīt occur, then you
> will have a losing situation.
Larger coils will have significant self-C, which behaves (at Fo at
least) virtually the same as the lumped C at the top.
>
> So the way I see it is:
> The bigger CToroid is, the less often you will experience a real arc (to
> something grounded), but the longer and more powerful this arc will be.
>
OK...
> The way I read some of the answers is that you can store a charge on the
coil
> itself (which has to be a very small amount).
>
> However, as soon as breakout occurs, you will lose this (and some of the
> energy stored in the toroid) into making your sparks and it takes quite a
> while (compared to the total time of one complete energy transfer cycle)
> before a new secondary "charging" cycle takes place. So, what I donīt
> understand is how can the stored energy from one cycle be carried over to
the
> next one?
Streamer loading, while substantial, is usually not sufficient to
completely deplete the entire stored energy in the coil and toroid in
one cycle of Fo unless it's a diurect hit to ground. In some cases,
breakout will occur BEFORE the primary:secondary energy transfer is
complete, so EM energy from the primary circuit can couple more energy
to the secondary (and streamers).
>
> Another one of my question to the "resonant believers" is:
>
> If resonant rise does occur, why doesnīt the output (spark length) of an
> unloaded (!!) coil continue to grow the longer the coil operates?
With no topload, energy losses from premature breakout occur much too
early in the primary-to-secondary energy transfer sequence, such that
the secondary voltage can never approach it's unloaded limit. The lack
of a relatively large lumped C at the top also negatively impacts the
formation of streamer formation/propagation, since the large
instantaneous currents required for streamer propagation will
immmediately collapse the voltage at the top of the coil, stopping the
streamer propagation process. It takes high voltage AND high
instantaneous currents to form the hot streamer and arc root necessary
for streamer extention over multiple bangs...
> Of course
> there would be a limit to this, but any (unloaded) coil should experience
very
> short streamers that will (have to) grow in length the longer the coil
runs. I
> have never seen this happen.
> I do not mean that some arcs or streamers are longer than others. Resonance
> rise would force MOST streamers to continue to grow in length. Esp. since
the
> energy needed to keep a streamer alive is less than is needed to let a new
> streamer form. In other words: when you plug in your coil you start out
with a
> streamer of say 10". After a minute of running, this streamer would be
(e.g.)
> 20" long, etc. Plus a coil experiencing resonant rise shouldnīt
experience the
> dramatic differences in arc length (loaded vs unloaded).
>
> The experience with my (unloaded) coil has been that I get a (or multiple)
> streamer(s) of 20" and this length does NOT vary all too great.
It's reached an energy balance that spreads out the transferred energy
over a large number of individual sparks. These don't coelesce into a
single, hot streamer, letting the air cools down too much betwen bangs.
That's why they aren't growing from bang-to-bang...
> The streamer
> will connect to a grounded rod now and then (which is a little further away
> ~2"), but if I place the grounded rod say an additional 2-4" away, the
> streamer will never (!!) connect to it. If resonance rise DOES occur, it
> should do this after a while, but it doesnīt.
>
> A loaded coil will do this (growing arc or streamer length) to some extend,
> but I believe this is due to the fact that voltage is being stored on the
> toroid (!) and
> slowly building up, before finally discharging.
>
Nope. This is purely streamer extension from bang-to-bang. There's no
"carryover" of any energy from one bang to the next other than some
thermal energy left in the former arc channel and some residual
ionization. This is enough, since it leaves a weakenned region in the
air which is more easily re-ionized during the NEXT bang, so that the
next streamer can follow much of the path of it's predecessor, extending
the NEXT streamer a bit more. Eventually, the overall energy dissipated
over the streamer/arc path is balanced by the maximum amount of bang
energy available, and the process "stabilizes" to a maximum streamer
length. Increasing the break rate increases the power going into the
streamers as well as reducing the cool-down time between bangs. Both
factors tend to increase streamer length.
> What am I missing I.e. why do some guys (even experienced coilers) say a TC
> encounters resonant rise?
>
> More confused than ever before,
> Coiler greets from germany,
> Reinhard
Hope some of the above expnations clear up some of the mystery...
-- Bert --