Suggestion on Power Supply?

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

Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>


I've got a secondary coil that's 25.5" long by 6.625"
in diameter, 22 AWG.

I've got ducting for toroids 6, 7 and 8 inches cross
section, and about 10 Maxwell .03uF 35KV pulse caps
that I can arrange in any order for just about any
capacitance or voltage. The primary is now going to
be 2" brass strips totalling .045" wide, approximately
15 turns max.

I've ran all the simulations electronically in
microsim, my Tesla perl module, as well as JAVATC,
and any number of possibilities exist for topload,
power and tank capacitance. JAVATC says I can
expect sparks up to 9 feet in length, which would be
just dandy. (does this program consider resistance
from the spark gap?)

Of course, in the real world, inputs aren't as easily
chosen as they are for simulations.

The two major remaining variables in my design are
selection of the power supply and spark gap.
I initially wanted two 15Kv/60mA NST's in parallel,
but decided that was not going to be enough current
to charge a .03uF tank capacitor. From my
calculations, I figured it would take at least
15Kv/270mA to charge the capacitor in 8.3 ms.
(AC half cycle), which I think can only be handled
by a pole pig. (that's 4KVA) A PT just won't do
because it'd always be run over it's ratings.

Now, the biggest circuit in my house is 240VAC wired
to a 30Amp double breaker, which provides 7.2KVA to
a sauna heater rated for 6KVA. (Hey, this could be
a ballast too!, now where'd my ammeter go....)

I guess I've been a little hesitant to make the
move from 120 to 240...but I think my setup warrants
it whether i like it or not :) It may actually be
safer because running wires for 240VAC -at- 30Amps
is a lot less riskier than running 120VAC -at- 60Amps.
(I am afraid of wires burning in the walls...)

So, should I try and get 240VAC 5KVA pole pig or
reduce my capacitance to something smaller? (Which in
turn would affect the frequency, which would affect
the topload, amperage->spark gap etc...)

Also, I would like to run the coil with one of my
15KV/60 NST's -- or even smaller, as a method for
low power tuning and adjusting. Then, switch a few
cables around and run it at whatever it wants :)
(270mA...) Does anyone do this, surely you don't
go full blast from the start...

Next, I've got a bunch of 1/8" thoriated tungsten rods
left over from my first rotary spark gap. Are these
too small for the power levels involved now? I'm not
worried about them melting or anything like that, it's
just that 1/8" seems awful puny to carry 500 Amps.
I've seen SRSG's made with them before, but I would
think their "on" resistance is high...why have a large
capacitor when it's energy is going to be choked by a
high resistance gap?

Would 1/4" tungsten be better?

I have an idea for rotary gap that involves this:
four 5/16" diameter tungsten balls pounded into a
1/4" thick sheet of G10. They're not flush, 1/32"
sticks out from the disc on both sides. This rotates
between four stationary electrodes, two of which are
connected to each other. For the stationary electrodes
I would like to use the 5/16" or 1/4" TIG welding
electrodes that screw in to torches. (They have small
.025 diameter holes in them), but I am unsure of what
they are made of...it looks like copper, but I don't
think it is...does anyone know? I used them in a lower
power coil once before, and they appeared to work, but
I never ran it for very long or at high power.

The other option is a sucker gap...but that works best
with resonant sized capacitors...which brings us back
to the capacitor/power question...

Hope that's not too much! Have a good night everyone!






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