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Modeling a magnifier
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From: Antonio C. M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent: Thursday, March 12, 1998 10:05 PM
To: Tesla List
Subject: Re: Modeling a magnifier
John H. Couture wrote:
> I do not think the ground side of C3 should be hard wired to L2 as this
> does not truly represent the TC secondary circuit. Your test circuit should
> include an actual toroid (C3) in space with the earth (or metal plate) as a
> ground.
In the schematic, the lower line represents ground, and a distributed capacitor
(the toroid) works (almost) exactly as a capacitance to ground.
> I do not believe there will be any oscillations because the
> radiation resistance (Rr) will be greater than
> sqrt(4L/C).
In a series RLC circuit, the quality factor is: Q=sqrt(L/C)/R. For no oscillations,
Q<0.5, or R>sqrt(4L/C), as you say. In my test system, L=32 mH and C=5.34 pF.
This gaves R=154822 Ohms! The DC resistance of the coil is 142 Ohms, and the
measured equivalent series resistance at the resonance frequency is 1000 Ohms.
And the oscillations are clearly visible, with Q=77. The system is far too small
for any significant irradiation.
Even if I add a large toroid, R increases slowly, proportionally to 1/sqrt(C),
and there is a huge margin.
> After the gap has quenched (one shot) the toroid will
> remain charged and will discharge as an aperoidic wave. However, the
> question is "To what voltage should the toroid be charged in the test?" I
> have not been able to find anything on this in the literature.
At low power, I could verify the relation Vc3max=sqrt(C2/C3)*Vc2max quite
precisely. More precisely if I consider the loss caused by the series resistance
of L3. All the measured waveforms follow closely the simulated values with the
simplest model.
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq