[Prev][Next][Index][Thread]
Modeling a magnifier
----------
From: Antonio C. M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent: Saturday, March 07, 1998 2:14 AM
To: Tesla List
Subject: Re: Modeling a magnifier
bmack wrote:
> The magnifier is a very interesting subject and somewhat of an
> inigma. Not the least of which being the difference between coiler's
> empirical results and the CSN. Tesla noted that all three systems
> were the same resonance, but no one on the list (as far as I know) has
> a magnifier working in this mode. Perhaps there is an energy level and
> geometry that that forces this?
Not energy level, as the system is (without breakout) essentially linear.
I couldn't find yet a description on how the magnifier should work
anywhere. What I wrote is simply consequence of the structure of the
system.
> In a two coil system, the secondary is high Z when out of tune or
> shorted,
> impling a series tuned scenario. In the above 3 coil model using a "high
> value"
> for C2 will be minimum impedance when off tune. A simple experiment
> will prove /disprove this.(JM)
What you tried to say above is not clear to me. L3-C3 are in series.
The considerations about this model are valid for any values of the elements.
> > An interesting posibility is L2*C2=(L2+L3)*C3, with L1*C1 somewhere close
> > to this (I didn't verify exactly what would be the best).
> > With this relation, the combination secondary-third coil behaves exactly
> > as the tuned two-coil system of a normal Tesla coil:
> > assuming that L2<<L3, this makes C3<<C2, which defeats the ability
> to hold off the breakout potential...or are you proposing an
> alternative?(JM)
The model says that if L2<<L3, some capacitance shall be added to C2 for
optimal performance. Otherwise the system is equivalent to a conventional
coil out of tune, and the maximum possible voltage over C3 is never reached.
Note that C2 includes the self-capacitance of L2, the interconnections, and
the input capacitance of L3. If L3 can be consided as an 1/4 wave resonator,
it shall show a high-impedance condition at a frequency twice higher than
the series resonance of L3-C3, what adds a capacitance to ground at the
input of the L3 coil equal to 1/3 of the self-capacitance of L3. The effective
C2 is never less than this value. With an additional top capacitance in L3,
this value increases, getting closer to the entire self-capacitance of L3.
> From a recent post by Ricahrd Hull, C2 is nothing more than Isotropic
> capacitance of L2 and the oversized top turn forming a corona ring.
> (very small compared to C3).(JM)
More probably not, for the reason above, and also because too small C2 makes the
system behave as if L2 and L3 were two inductors in series. As mentioned
by several posters after I proposed exactly this model (C2=0) at the start
of this discussion line, This resusts in incorrect predictions for the dynamics
of the system.
> > Did you observe some amplitude modulation in the secondary waveforms
> after
> > the opening of the gap? The greater the modulation, the higher is the
> voltage
> > obtainable at C3, according to the model.
> >
> No, but then again I wasn't using a gap, mostly CW drive to observe
> the resonant frequency. You must be looking for the beat frequency
> against L1C1 to obtain the modulation-right?(JM)
Really, with CW you don't see the transients, but with the system tuned as
I describe, two (possibly very close) frequencies of maximum output should appear.
With that model, the secondary coil resonates with the third coil producing
beats, after the primary circuit is disconnected.
I will try to make some low-power experimental measurements to see what really
happens, and will post the results here.
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq