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Re: Hello from new Member

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hello Mat,

Snips of what you wrote you wrote with comments interspersed:

Hello to all.

I thought I should introduce myself as I will no doubt be seeking much help as I embark on my first Tesla coil project. :-)

I am planning on building my first coil ASAP and would be gratful for any help and advice you may be able to offer. I would like to start of by building a medium sized coil (I know I should really start with a small one but I have this habbit of trying to running before I can walk ) 

I'm sure that I'm not the only one that will probably tell you this, but
you really should start with a smaller one to "get your feet wet".

but I would like to produce a coil that will produce stremers of at least 15ft to start with. I am mad (probably) :-) but i fell that with my electronics knowlege and willing to learn feel this may be just possible with your help.

Medium size? I think most of us would consider a coil that produces
15 ft. streamers a LARGE coil. Unless you have a professional back-
ground in something like utility electrical engineering, I would strongly
suggest that you start out with a smaller coil for your first project.
Basic or even advanced electronics knowledge alone certainly does NOT
automatically make one an expert in the design and construction of large Tesla
coil systems! There are many things that can and usually do go wrong when you
start trying to fire off a coil of that magnitude. Of course the biggest danger is
the electrocution hazard of the primary circuitry of a large coil. One
mishap of physical contact with this voltage will usually result in DEATH!
What you're wanting will probably require a minimum of 15 kVA's worth
of distribution transformer (that would usually weigh from 300 to 400
lbs here in the US) and to my understanding, these transformers are
even more massive in relation to their kVA rating in Great Britain.

Also, unless you have very substantial funding at your disposal, you
are going to find a coil of this proportion to dig very deeply into your
pockets (likely $1000s or pounds in your case). Since many things
usually go wrong during the "learning curve" of coil building, smoked
parts can get quite costly while you're "learning"! For example, it's
a whole lot cheaper (and simpler) to replace just about any part of a small
NST or OBIT powered coil than to replace its counterpart of a large
coil system. "Learning" may be something that you are unable to afford
with a big coil!

For this size coil would it be more prudent to go the Power distribution transformer route or a bank of MOV transformers ect. As i can see advantages in both. and would a coil this size be best suited to a Rotary spark gap or static .. ect.

If anyone has any thoughts on this I would be very gratful for your input.


Thanks in advance 

Well, if you ARE determined to build a monster for your first coil project
then you would definitely need to look for a power distribution type trans-
former for your power supply (we call 'em "pole pigs" here in the US) and
it would need to be around 15 kVA rating with over 10 kV for the high
voltage side of it. You will also have to build in some sort of ballasting as
these type of transformers are NOT current limited. Some people have
successfully multi-ganged MOTs (microwave oven transformers) to po-
wer larger coil systems but it would take a pretty good number of them
to get the power that you're after.

As for a spark gap, you would almost certainly have to go with a rotary
type to be able to quench and that's another whole set of design chal-
lenges for a beginner coiler. A coil of this magnitude may require a combi-
nation a two or more seriesed spark gaps (like a main rotary gap in series
with a stationary gap system) to commutate the spark of the spark gap
to be able to properly quench. Even many advanced coilers opt to
have the rotary gap professionally build by a machinist than to try to
tackle this on their own.

I ceratinly don't mean to discourage you, but to put it in your own words,
"you're trying to run before you learn to walk" and I think that you'll find
that most of the rest of the members on this list feel basically the same
way about this. There are many factors that can't be covered in a short reply
to your questions here and the only real way that most coilers are going
to be able to get answers to all of their questions that they don't even know to
ask is to start out with a small NST powered coil for their first project and
then go on to building progressively larger coils as they learn from experi-
ence along with the technical knowledge. That's how "most of us" go about
it ;^)

Mat 

David Rieben