Re: Proposed capacitive transformer TC?

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

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>

> I am aware that some sort of "feed plane" between the topload and ground
plane
> (and capacitively coupled to both) would be required and it would have to be
> designed so that it did not unduly interfere with the magnetic field
generated
> by the "secondary" coil (L1) -not a correct definition as there would be no
> "primary" and therefore no inductive coupling.

Maybe just an insulated metal plate under the secondary coil, as a
ground
plane, but not connected to ground. The plate shall have a hole in the
center for the base of the secondary (grounded), and may have a section
cut away to avoid the formation of a single turn around (under) the 
secondary.

> The feed plane would of course have to be fed with RF either from a generator
> or a from a spark-gap.
> 
> I am thinking of starting small to test the concept without entailing excess
> cost e.g.. so am considering building a "mini-coil" using 40SWG wire on a
> plastic vitamin pill container for L1 and a flyback transformer to fire a
> spark-gap connected between the ground and the feed plane which might be a
> horizontally-mounted metal sheet a central hole big enough for the coil to
> stand vertically within it without actually touching the metal sheet. Or
maybe
> the feedplane could be a non-inductive coil surrounding L1 and connected
> between the PSU and the spark-gap with the insulated wire double-backed
so that
> the magnetic fields cancel leaving only the electric field to interact
with L1,
> the output inductor.
> 
> If the proposed device were constructed, is it at all likely that there would
> be enough capacitive coupling between the feedplane/ground capacitor C1
and the
> parallel-resonant circuit L1-C2-C1 to allow sufficient energy to be
transferred
> from the former to the latter for the production of sparks or streamers?
> 
> Finally, would it permissible for me to submit *.jpeg or *.bmp images of the
> device to the TCML for further reference and comment?

Use ascii art, or put the pictures somewhere in the web and post the
links.

The system can surely be built, but two coils are needed. The schematic
diagram may be as:

                     (=====) Terminal
                        |       
                        L2      
                        |       
 o------+--L1--+-----===|=== Electric induction plane
        o      |        |
PSU    gap     C1       |
        o      |        |
 o------+------+--------+--o Ground 

L1 is not magnetically coupled (significantly) to L2. A
capacitor C2 is formed between the induction plane and
the body of L2 and the terminal.
A lumped model for this circuit is:
                       
 o------+--L1--+--C2--+
        o      |      |
PSU    gap     C1     L2
        o      |      |
 o------+------+------+--o Ground 

Interchanging L1-C1 and L2-C2, what doesn't make diference
once the gap fires, shows that the circuit is equivalent to the
directly coupled Tesla coil that I described some days ago. 

I can easily modify my system to this configuration and see 
what happens.

This system has an inconvenience: It's not possible to choose
independently the equivalent of the coupling coefficient in
a Tesla transformer and the voltage gain. The maximum voltage
gain with reasonable coupling appears to be around 20. My system
is tuned to 9.53, and works.

Antonio Carlos M. de Queiroz