Re: New Twin 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>
> 
> 1)For L1/C1 would a transformed value of inpedance be permissible e.g. would
> tapping L1 at some point between C1 and ground be OK?

There is a solution in this form, but the elements would be somewhat
different. The main problem is that the coupling in the autotransformer
will not be unitary. This causes the impedance of the L1C1 tank to
become inductive at high frequency instead of capacitive. An exact
design for this configuration would be of 6th-order, magnifier-like.
An approximation that can work is to tap L1 at a point that halves the
impedance of the L1C1 tank, leaving 0.707 of the turns between the
tap and the ground. With a reasonable coupling in the autotransformer
the system will work correctly. The energy transfer will be faster, but 
the voltage gain will be lower, because the output capacitance with 
two resonators is doubled.

 > 2)For balance, would it be possible to measure ground current/
voltage from
> the base of L1 to true ground and attempt to get a minimum value e.g could
> the brightness of an LED or neon bulb connected between L1 base and ground
> act as crude indication that balance has been obtained?

Perfect tuning will minimize the energy circulating in L1C1, and so
measuring the average current in L1 and minimizing it will work.
I didn't try this, but the idea is theoretically correct. Use a small
resistor in series with L1, at the ground side, and measure the AC
voltage over it. You can also add a diode-RC detector in parallel
with the resistor and observe the DC output, maybe with a LED.
 
> 3) Following from 2) since network is a bridge and voltage from a position
> midway between the resonator terminals (a and b) to ground is theoretically
> zero at balance
> doesn't the circuit have potential as a measuring bridge for capacitance and
> inductance?

A very complicated one...
 
> Incidentally, I am presently getting higher voltage from the capacitive
> transformer (L2) than from the directly-coupled (L2') branch of my TC, the
> output from L2' decreasing  as it is moved closer to the influence ring .
>  Is it possible that the "better than expected" performance of the
> capacitive transformer L2 is a result of a tightly-coupled influence ring
> splitting C3 in half  (in which case  it  MIGHT be OK to connect the
> influence ring surrounding L2' to ground instead of the base of L2' as
> indicated) or are there just too many other variables to be considered?

There are other variables to consider. With the original primary, the
system may have a tendency to couple better to one branch than to
another, but poorly to both.

Antonio Carlos M. de Queiroz