Re: Transformerless Tesla coil

["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>
> 
> Antonio,
> 
> Apart from being a bridge isn't the  proposed twin transformerless TC
> actually a pretty good BALUN -to use the radio terminology- as it has
> unbalanced input and balanced outputs?

The application is quite different. In this case the transformation
is from the energy in a charged capacitor into balanced oscillations
in two terminals. Baluns are basically just transformers.

> Also while it may be more difficult to tune, wouldn't it be more economic
> and less complicated  to build than most of the other twin-Tesla coil
> configurations that have been published -after all, I can foresee twice as
> many primary components (2 x L1, 2 x C1), balanced-output HV transformer and
> centre-tapped grounding for a twin TC done the other way!

A conventional twin would have a single primary capacitor and two
complete Tesla transformers, with the phasing of the transformers
adjusted to result in balanced outputs. In this directly/capacitively
coupled twin the two primary coils are replaced by a single off-axis
inductor and two "influence planes".
  
                         (=====)a    (=====)b
                            |           |
                            L2          L2'
                            |           |
     o------+--C1--+----(=) | (=)---(=)-+-(=) <-Two influence planes
            o      |        |
    PSU    gap     L1       |
            o      |        |
     o------+------+--------+---------------o Ground

The construction is really simpler. But this system would probably
not achieve the performance of a classical twin Tesla coil. Its
dynamics is the same of a "capacitive transformer" coil, with the
strong limitation of the compromise between many cycles for complete 
energy transfer and low voltage gain.

An interesting aspect, however, is that this circuit produces
twice more output voltage than the equivalent capacitive transformer
coil for the same input voltage.

Antonio Carlos M. de Queiroz