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Re: [TCML] General Questions About a Pig Powered Coil (and an Introduction)

Hey Thomas...

Pig powered coils are quite capable of 6'+ streamers...

Things to consider are
Piggie output voltage and KVA
Secondary size
toroid size
Spark Gap
Capacitors available
Amp rating of the variac in single phase mode

Most piggies used in coiling run 14.4 KVAC at 10KVA
Secondary size range from 8" - 12"dia at 45" to 60" in length with wire at 16 - 20 ga for 1000 or so turns Toroid size is somewhat relational to secondary size e.g. overall toroid dia = secondary length and toroidtube dia = secondary dia.
this is just a rule of thumb not written in stone....
Spark gaps for piggie coils get a severe beating, best bet would be to use a synchronis rotory spark gap ( spinning disc type) with tungsten electrodes Capacitors get to be "big" to handle the voltage and to make use of the quick charge time offered by piggies When using a variac, most of the time it requires 2 or 4 units in a parallel connection scheme to handle the current
( this normally applies to 1256D units or similar sized variacs)
Since piggies are not current limited, some type of ballasting is required, be it resistive ( works but is inefficient) or inductive ( best option) to limit the current to the piggie. Safety is not just a term to consider when doing piggies... you breathe it, eat it, keep it on your mind consistantly when doing piggies, Obits, NSTs, are capable of leaving you alive if you get bitten. Piggies can kill with their lethal bite....

Now for the questions....

The variac you have,  is it 3 units stacked on a single shaft?
What size piggie do you have or plan to get?
Do you have 240VAC available ( electric clothes dryer, electric stove/oven)?
Do you have the available area to run a pig powerd unit?? ( Shop/garage/outdoors)?

feel free to keep asking questions here lots of knowledge to be gleaned from the list

Scot D

Thomas Schmit wrote:

Hi Everybody,

I've never used a mailing list like this before, so you will have to
excuse any faux pa regarding the use of said list. For a quick bit of
background, I am a machinist and high energy physicist and it seemed
time that I build a Tesla coil. (No self-respecting physicist can
neglect to build one ;-) ).

I have a 3 phase variac (used for a cloud chamber, originally - its
good to 100 amps and 600 VAC RMS), a single phase pole pig, an old
mil-spec 30 KVDC 5 ma supply, several neon light transformers, etc.
That being said, I'm new to the home-brew high voltage game. It is
considerably different than working for a lab where dropping $10,000
on a power supply is trump change :-D and I could use all the help I
can get!

What I am concerned about now is the design of my coil. I am building
with a 6' spark in mind - that should pretty well max out a 110 volt
supply (the pole pig will be fed through one of the variacs hooked
into 110 volt mains through a 30 amp breaker). I'm looking at a
secondary coil with about 1000 turns of 23 AWG wire, which works out
to a length of only about 25". I am concerned about strikes hitting
the primary coil from the discharge terminal on the secondary.

I guess I was just hoping I could get some input on the secondary
design. I'm thinking an 8" diameter PVC form - I will clean, bake and
shellac it before winding my coil. Size/length/diameter of wire/number
of turns - these are all variables that I'm not to sure about. I know
what inductance I want to hit, but I can get there several different
ways and I figure you all have already done the hard work for me ...

Tom Schmit

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