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Re: The Sigma-6 Coil-Magnifier?

Original poster: "Christopher Boden by way of Terry Fritz <twftesla-at-uswest-dot-net>" <chrisboden-at-hotmail-dot-com>

>Original poster: "Malcolm Watts by way of Terry Fritz 
><twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz.pupman-dot-com>
>       Are you quoting an accepted "wisdom" or tenet?
>On 16 May 01, at 18:33, Tesla list wrote:
> > Original poster: "Matt Shayka by way of Terry Fritz
> > <twftesla-at-uswest-dot-net>" <flyboxboy-at-hotmail-dot-com>
> >
> >
> > Why not build a magnifier on that scale? It would produce much larger
> > streamers and lightning with your 10kVA pig than a conventional coil.
>Why should it? A technical reason would be most convincing.
> > It would not be as bulky, either. Well, if you have your mind set, go
> > for it. I just thuoght it was a good idea.
> >           -Matt Shayka
> >

Right now I'm designing the power cab. I spent about 14 hours today hunched 
up working inside it :) I'll get some pics when Betsy (the photographer for 
the Group) gets her car fixed, a couple days.

I'm designing the system to run from 240VAC input, with an output of 120VAC 
for the controls (internal to the cab), 0-120VAC -at-20A for the SRSG (or an 
ASRG in the future), and the main out of 0-280VAC -at- 60A (though I think I 
can safely pull 75A for short runs through the variacs).

Ok, some dumb questions .....

Looking at the standard variac wireing diagram for GE Variacs (and most 
others I've seen) located at 

1. For a 240 input and 0-280 out I connect one of the 120 legs to 1 and the 
other 120 leg to 2. Output hots are 3 and 4 and neutral is fed straight 
through with no neutral connections to the variacs at all, right?

2. What are 6 and 7 for? Using the autotransformer effect if I connect my 
input to1 and 7 instead of 1 and 2 I would get an even higer voltage out 
right? How far can I push this? Can I use 1 and 5 and get demonic voltage 
levels out? (this is useless as the pig would saturate WAY before I got it 
all the way up, if the insulation didn't breakdown first. Just curious.)

3. What are 8 and 9? I don't even know if these appear on my variac, lol, 
though I think they might.

The Sigma-6 Twin coil now has a name (thanks to Josh). It is to be called 
the Gemini Project, being a Twin coil and all. Not to mention, I'm a Gemini 

I'm sticking with the twin setup, though in the future I'm sure we'll have a 
large magnifier. But as I see it, a twin, for this application, is the best 
solution of the 4 basic coil types. I like the idea of pulling 30+' arcs to 
each other. I like the idea of being able to do a LOT of experimentation 
with things like Equidrive and such. I like the idea of having a (somewhat) 
controlled output. Without the use of REALLY high powered lasers (something 
noone has pulled off yet) this is the closest to being able to "aim" a coil 
that I've seen.

It's a big project, but easily practical. It's something that we can 
reasonably build without spending a lot of money, and it will be very 
usefull in demos and research. It's a great project for Sigma-6.

Just wait till we have the HVL (High Voltage Lab) online :)

Today I cleaned out the cab from it's former life as an X-Ray control cab. 
REmoved EVERYTHING but the variac. Then I recycled the following...

A pair of BIG 15 breakers from the old mill are now the interim mains 
breakers for testing and design of the control circuitry. When I finish the 
cab I'll replace these with a pair of 50 or 60A breakers.

About 20' of 8AWG for the mains wiring to and from the breakers. And a BUNCH 
of 18-22AWG for the controls wiring.

A few interesting meters. Milliamps, KVP, and Kilovolts. MANY more to 
come....when I figire out how to make the holes without a drill 

Some lighted industrial buttons, and a SPDT switch (to be replaced by a 
keyswitch in a couple days) from the old mill. Buttons are for...

Keyswitch, panel enable (if it's off power is cut through a contactor across 
the mains and NOTHING in the panel will work.)

Emergency off (shuts down EVERYTHING after the mains breakers) and requires 
a manual reset (push another button).

Dual, red, guarded pushbuttons to fire the coil. They have to be both 
pressed simoutaniously.


Switch and variac for Rotary gap.
Panel interlock microswitches (opening any panel in the cab cuts mains power 
unless a interior switch is set to test)
more switches and buttons to control almost any aspect of the coil and 
support gears operation.
Meters Meters Meters
2 interior work lights, 1 on each level, for working inside the panel in a 
darkened room, or outdoors after dark.
Alarm horn, and strobe light, they come on when panel is armed, and off when 
the coil is fired. Alarm is on for only 1 second at initial arming, strobe 
is constant.
A pair of "Tethers". These are hand held SPST emergency off switches to be 
used for large public demos. Two crewmembers will hold them, one to either 
side of the panel. In the event they see something, ANYTHING out of place, 
they simply hit the button and the panel goes into an Emergency Off state. 
This has happened a couple times where someone other than the operator can 
see something that he can't and sometimes hand signals take too long to 
communicate. It's far easier to hit a button yourself. Each tether will be 
about 50' long.

btw the panel will be put through the most severe testing we can think of 
before it ever sees a coil. We're already coming up with ideas to abuse 
this. We want to not only see how good we can design something, but make 
sure that under NO circumstances will it fail during a demo or in other use.

Any other ideas? Suggestions?

Terry, I'm finally getting to use the filter I got from you almost a year 
ago :) It's for 3Ph, but I'm thinking of using the 3rd wire for Neutral, is 
that OK?

My kingdom for a set of knockouts, lol.

Have fun!


Christopher A. Boden Geek#1
President / C.E.O. / Alpha Geek
The Geek Group
Because the Geek shall inherit the Earth!

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