SSTC Input Supply Controller

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

Original poster: dhmccauley-at-spacecatlighting-dot-com 

Now that my two month tesla coiling hiatus is over, its back to work.  As
well as working on my first magnifier coil, I am designing a high power
input power
controller for SSTC use.

First, a brief summary on the operation of the typical SSTC using a
full-bridge or similar configuration.  An input signal is fed into the SSTC
driver circuit and "chopped" up
at the resonant frequency of the resonator coil.  This results in a high
voltage output at the top of the resonator coil.

Now, the biggest determination in how the output spark looks like is what
this "input signal" looks like.  Most commonly, we use either 120 or 240VAC
half-rectified (through
a single diode) or a DC input.  Half-Rectified input usually results in
longer arcs while DC input results in short, bushier arcs which is most
commonly used in audio modulation due
to the quiet properties of this CW type discharge.

What really hasn't been done too much yet is to explore the wide variety of
input signals which can be used for the SSTC.  A few have tried varying this
(i.e. Richie Burnett) and found
that these input waveforms have a profound effect on the output appearance
of the SSTC.

As part of my newly found desire to do some serious research, I propose to
build a high power input SSTC controller which will be able to produce a
wide variety of input
waveforms at up to 340VDC and about 1kW total power.  I plan to use an
advanced microcontroller system to control a linear output amplifier capable
of producing DC output, sawtooth, pulse, stepped sinewave, and other type of
waveforms with full user programmability.  For example, I could probably a
waveform with up to 100 discrete levels and able to reproduce
lmost any waveform imaginable.  Also output frequency could vary from 10Hz
up to maybe 1kHz, and duty cycle could be adjusted as well.
The microcontroller programming is very easy, and the only crux in this
design is the actual cooling scheme for the linear switching element (FET
etc...)
which will mostly be operating in the linear range.

I believe with such a set-up, a lot could be found regarding the output
apperance of arcs and the RF envelopes ultimately creating them.  In fact,
we may be able to reproduce those
VTTC super-straight swordlike streamers with something like this.

This weekend, I'll be updating my website with my preliminary designs and
ideas on this controller.  Should be fun!

Dan