Re: [TCML] BIG solid state

[Steve Ward <steve.ward@xxxxxxxxx>]

Hi Greg,

I wasn't aware of this article about your 120L coil, I really like the use
of a car engine as a power source, how well did that work for you?  Im also
curious to extract more information about how you changed the tank Z and
obtained such a large improvement in efficiency.  Did you also increase the
charging voltage for the capacitors by some factor of sqrt(3) to make up the
bang energy from cutting C to 1/3?  Or i guess you were making bigger sparks
with less energy (as input power went down), but still maybe had to bump up
the voltage somewhat?

And furthermore, what do you think the real impact was of increasing the
toroid?  Do you think the benefits were mostly from dropping the resonant
frequency?  Or do you think the lower secondary impedance was better suited
for driving power into streamers?  I personally am questioning whether or
not i really need an 8 foot diameter toroid, or if i could get away with ~6
foot diameter (that way i can use 20' lengths of aluminum tube to make a
multi-element ring toroid).  I had often looked at some of your big coil
projects to try and make some decision on whether or not the monster toroid
was required for making monster sparks.  If it means i have to put in an
extra 10% power with a smaller toroid, it might be worth it.

There really weren't any big technological hurdles in the building of this
DRSSTC, though I have been working extensively with this topology for the
last 6-7 years or so, this was merely the next step up in size (the details
of the electronics are pretty well understood by now).  With no specific
project schedule, i pondered the quad primary drive for about the last 2
years, which in my opinion is the only "new" thing going on here, and even
that seemed too easy once it was actually implemented.  De-bugging took just
a few hours.

The main thing preventing it from happening for so long was really just a
lack of man-power.  The scale of things was just beyond what i could do by
myself in the garage.  Getting people together to work on projects is always
harder than it should be, especially when there is no deadline involved.

Steve

On Wed, Jun 15, 2011 at 9:06 PM, Greg Leyh <lod@xxxxxxxxxxx> wrote:

> Hi Steve,
>
> Great work!  Getting a complex HF solid-state drive system to work at 33kVA
> is no small feat.  The coilform seems nice and compact too for that
> throughput.  At 480VAC input and 25ft arcs, your new DRSSTC is comparable in
> many ways to the 120L Experimental Coil, described here in the TCBA news,
> summer of 1990:
>
> http://www.lightninglab.org/gallery/3rdStLab/TCBA_GELeyh.pdf
>
> In 1998 we increased the 120L's primary Zchar from 5 to 15ohms, greatly
> reducing the rotary gap losses, then doubled the toroid size.  These two
> changes reduced the wallplug draw from 40kW down to about 25kW and increased
> the arc length to about 25ft, bringing it roughly in line with the old '1kW
> per foot' benchmark.
>
> What would you say has been the most difficult aspect in realizing your new
> DRSSTC coil?  -GL
>
>
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