Successful SSTC Audio Modulation - SWEET!

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>

After a day of extreme frustration (yesterday gate drive problems) and a
simple re-design of my gate drive topology, i finally got my SSTC to run
from the push-pull outputs from the
TL494.  So now, I have 25% on-side1, 25% deadtime, 25% on-side2, 25%
deadtime.  This is required as operating in CW mode consumes mucho power, so
by running the coil
this way, you can reduce total output power and improve reliability of the
h-bridge switch.

Audio was provided by a CD player (high impedance output) and fed into the
deadtime comparator pin of the TL494 through an 0.1uF capacitor.

Audio output was very clear and almost zero noise otherwise from other
harmonics in the arcs.  Very impressive, similar to Sue Gaeta's high side
modulation audio quality on her 811A
VTTC.  Also, with fan cooling, the heatsinks and FETs never even really get
warm.

One note to add, is that to improve audio quality, it is necessary to
draw-out a continuous white flaming arc from the toroid.  This can be done
by any metallic object and permanently set at about
a 2-3 inch gap depending on output power levels.  The result is stunning
audio.  (at least stunning when considering its coming from a hot flaming
multi-kilovolt arc ! ! !)

Also, volume control can be provided by adjusting this discharge gap
distance.  To get really loud audio, just try to stretch the arc as long as
possible.  I guess this provides much more heating of the air and therefore
more volume.

Awesome!

The Captain