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RE: PWM Controller question

Original poster: "David Trimmell" <humanb-at-chaoticuniverse-dot-com> 

Sue, you are indeed correct that bigger sparks will give a better
response to lower audio fr, I have seen this with my
AudioMmodulatedVTTC. But to get really long sparks you will need some
MAJOR power! I was able to get 10" sparks when first starting out with
audio modulation, basically staccato to the base with some major
clipping! But really we don't need really long sparks to get some really
clean LOUD audio, 4-5" plasma discharge will deafen you. If one could
find a way to get a larger more powerful discharge from Dan's
PlasmaSonic and get a way to easily tune to best mode for clean audio,
then we will have something really cool (not that it isn't already


David Trimmell

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, June 23, 2004 8:23 PM
To: tesla-at-pupman-dot-com
Subject: Re: PWM Controller question

Original poster: Sue Gaeta <sgsparky-at-prodigy-dot-net>

...and that was with a lousy modulation transformer!
I showed my project to a friend of mine who is a broadcast engineer, and
high fidelity freak. He is also an amateur radio operator with a home
brew  high fi AM transmitter. Just for sh**s and grins, he connected his

modulator and power supply to my VTTC. The quality of the audio was

The mod transformer that I have in there now is out of an old military
transmitter which is known for poor quality audio (an ART 13). If I
good fidelity I would have to use a transformer that was 4 times as
and would not fit in my modulator deck! Good high side modulation makes
a very bulky, and heavy rig, but the results are indeed cool!

I have this crazy idea that bigger sparks will give better bass
so I would love to see Steve Ward give his interrupter a rest, turn down

the rail voltage half way, and high side modulate that sucker! People
it can't be done, but it is done with 50, 60, 100, and 120 Hz all the
Finding a suitable mod transformer that can handle that much current,
has the correct impedance match would be challanging, and maybe even
impossible though. Someone once suggested substituting the mod
with an SCR or something. If someone could come up with a way of high
modulation with active power devices in place of a modulation
it would be great! Even if he settled with driver side modulation, I
love to see what kind of audio comes out of a 10 foot arc! The nice
about high side, high fidelity modulation is that throbbing base will
produce long streamers if you are fully modulating (ie: the rail voltage

will peak at double the! supply voltage with no modulation, and then dip
0 volts during an audio cycle).

Tesla list <tesla-at-pupman-dot-com> wrote:
Original poster: "Eastern Voltage Research Corporation"

  > > I think Dan's PlasmaSonic design is good, but I could see some
  > > improvements in using (possibly) rail modulation. Real high power
  > > audio modulation will be seriously cool! I have seen it while
  > > something "semi-grounded" to a AM radio station tower many years
  > > (don't ask!). My grid modulated VTTC has been the closest I have
  > > yet, but quality was unreliable.

Absolutely. This *is* the way to do it, although high-side modulation is
more involved and requires a lot more

Sue Gaeta's high-side audio modulated VTTC was stunning and definitely
performed the PlasmaSonic as far as audio quality goes.