Re: Ballast

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

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


As many have probably told you, ballasting for
_safety_ is usually not required in an NST 
(unless you do surgery on it.) 

But don't let that stop you from using one! :)

In a nutshell, inductors provide energy transformation
of an electrical current to and from a electromagnetic
field. A rising and collapsing electromagnetic field
will pump out a significant amount of voltage when
it's oscillating at some frequency. This is how we
get those big toroid sparks we know and love, but in
this example I am speaking of a different part of the
tesla coil circuit here.

A series inductor before the spark gap will actually
create _another_ LC circuit with your tank cap. If you
set the inductor's value to that where the cap
charging circuit resonates at 60Hz, every mains cycle
is going to pack more voltage into your cap. 

One caveat:

I wouldn't do this without an adequate NST protection
filter, a safety gap on both the main spark gap and
the NST. If there is something wrong with your main
spark gap and it doesn't fire when it's supposted to,
your cap voltage is going to rise to it's dielectric
breakdown voltage and explode. (That is, if your NST
doesn't explode first.)
 
This page is excellent:

http://www.richieburnett.co.uk/ballast.html#ballasting

-Jeremy

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Matt Morrissette by way of Terry
> Fritz <twftesla-at-qwest-dot-net>" <yinzara-at-MIT.EDU>
> 
> 
> Ok, well I ve been studying up on the tesla coil and
> reading through some of
> the past archives. I ve been reading that a form of
> ballast is needed in the
> circuit.  Right now I have a stationary spark gap,
> MMC capacitor bank, primary,
> secondary, and 12/60 transformer.  Do I really need
> a ballast and if so when is
> the cheapest way of going about getting or making
> one.  Also I don t know
> exactly how to make the safety gap. What should I do
> for either of these?
> 
>  
> 
> Matt
> 
> 
>