Re: Proposed capacitive transformer TC?

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

Original poster: "Jolyon Vater Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>

So to keep the coupling the same both C1 and C2 would have to be adjusted
which would change the frequency?

 Therefore to keep coupling coeffient AND frequency constant would it not be
necessary to change the inductance of L1 and L2?

Or to keep frequency the same but with different coefficient of coupling,
the total series capacitance of C1 and C2 would have to be constant but
effective parallel inductance would have to change and vice-versa.

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, July 29, 2002 7:19 AM
Subject: Re: Proposed capacitive transformer TC?


> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
> >
> > Original poster: "Jolyon Vater Cox by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> >
> > Is C1 formed between the electric induction plane and the ground
plane -or
> > will supplementary capacitor need to be connected?
>
> C1 is a discrete capacitor, as the primary capacitor in a regular coil.
>
> > What is the function of L1 and why is it necessary-  is it  to resonate
with
> > C1 perhaps? I am asking because  I envisaged the device I was describing
as
> > a capacitive autotransformer like a pi-tank or the tank circuit of a
> > Colpitts oscillator (albeit without the feedback arrangements)
>
> L1 resonates with C1, as in a regular Tesla coil. The tuning relation
> for
> the ideal system is L1*C1=(L1+L2)*C2. L1 must exist in a capacitor-
> discharge system, to form the primary tank, where the energy initially
> resides.
>
> > Coupling is capacitive. Would it not be possible -in theory at least- to
> > vary the coupling by varying the distance from the induction plane to
the
> > ground plane and topload without changing the ratio of C1 to
C2 -although I
> > surmise this would affect the resonant frequency somewhat.
>
> The main effect would be to vary C2, as C1 is already a large discrete
> capacitor, and extra distributed capacitance between the induction
> plate and the ground would make little effect. The system can be tuned
> in this way, given that L1, L2, and C1 are fixed. The equivalent of
> the coupling would change too.
>
> > Finally, could it be that the real advantages of this form of TC would
be
> > towards the higher end of the RF spectrum when coils are much smaller
and
> > more difficult to adjust than they are at low frequencies?
>
> The coils can't be much smaller than the usual sizes, since they
> operate with large voltage differences and enough clearances must be
> kept. This causes also the distributed capacitances to be limited
> to the regular values. But the coils can have less turns, with the
> system operating at higher frequencies. The restriction is that at
> some point it is not anymore possible to make a coil, since the
> inductance becomes too small. See my directly coupled system for
> example. The primary coil has 95 turns and the secondary has 1152.
> If these numbers are reduced to 1/10, to 9.5 and 115.2 turns,
> the system would (probably) operate in the same way, but the
> operating frequency would rise 10 times (to 2830 kHz), and there is
> still some way to go. The capacitances would remain the same.
> Directly coupled systems, that include the capacitive transform
> structure,
> since they don't require a large (in size) primary coil, apparently
> admit construction for operation at high frequency (a few MHz). There
> is the problem with increased losses due to skin effect (use thicker
> wire or tubes, since there is more space) and irradiation at these
> frequencies (not so intense for the usual sizes). Something to try.
>
> Antonio Carlos M. de Queiroz
>
>
>
>