Re: [TCML] CW magnifier

[Phillip Slawinski <pslawinski@xxxxxxxxx>]

Carlos,

I don't really see 90" sparks from an CW audio modulated valve coil.  If you
want that kind of spark length you'd be better off building a DRSSTC.
Unfortunately, as you mentioned there is a significant drop in audio
quality.  I don't know your system very well, so it's hard to really suggest
improvements.  How are you audio modulating now?  Do you modulate with the
grid, or do you modulate the plate voltage?

Given how much power you have available, 90" sparks should certainly be
obtainable in quasi continuous mode.  To obtain such sparks you will almost
certainly need a special supply for the plate.  At 90" you couldn't expect
much modulation.  You'd have to have a pretty low duty cycle to make sparks
like that, since the spark growth time would be pretty long, probably 20 -
30 milliseconds.  This means you'd have a big subwoofer.

-Phillip Slawinski


On Sun, Apr 3, 2011 at 01:22, Carlos Van Camp <carlos@xxxxxxxxxxxxxxxxxxxxxx
> wrote:

> Hi phillip,
> The arcs I am getting now are about 30-35" long with a CW input of 25-30kw.
> (the machine is capable of 50kw continuously)
> There are 6 electrodes on the secondary top load, each producing its own
> brush of arcs.
> They are like thick flames of plasma which branch into many tendrils of fat
> bolts.
> The problem is I need 2-3 times this to make the art piece asthetically
> pleasing and functional.
> To ad to the problem, the coil is also sound modulated... So Going pulsed
> instead of CW means losing some sound quality in order to gain spark
> length...
> I have no experience with pulsed valve coils, but have started down the
> track of making an audio interface circuit that converts the audio into a
> controlled square wave to feed onto the valve.(my electronics knowledge is
> pretty basic)
> I am not sure at this point weather to follow conventional thought, and
> pulse the cathode to ground, or to follow my gut, and drive the grid of the
> valve with bursts of rf (at the appropriate frequency of course)...
>
> Carlos
>
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