Re: John's formula, spark length

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

Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


A few years back I wrote an article for Harry Goldman's TCBA Newsletter and
updated John's nice equation.

I've attached it in it's original MS-Word format.

http://hot-streamer-dot-com/temp/TC-Design-1.doc

Dr. Resonance



----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, September 03, 2002 5:03 PM
Subject: Re: John's formula, spark length


> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<FutureT-at-aol-dot-com>
>
> Ed,
>
> My formula is not for the average coil, it is only for efficient
> coils.  If a coil needs to be large to be efficient, then my
> formula would call for that.  This formula does not take into
> account the size of the coil.  The purpose of the formula
> is not to predict how long the sparks will be from a particular
> coil.  Rather the formula predicts the longest possible spark
> length using a particular input power.  It is assumed that the
> most efficient size and design will be used to achieve these
> optimal results.  Of course some extremely efficient coils
> may do a little better than the formula predicts.  It's only a
> guide, and only a guide for efficient coils.
>
> I define an "efficient coil" as one that can give the longest
> possible sparks for a given input power.  This is not the
> true engineering definition of efficiency of course.
>
> I personally don't know if your coil would give much longer sparks
> if it was wider, for the same input power.  It may, since the
> inductance would be higher.  Sometimes much the same effect
> can be achieved by using a somewhat thinner wire with more
> turns.  Of course if the wire is too thin, the performance will
> be poor.  It's a balancing act.  I consider the length of the coil
> (the height) to be a very important factor in determining power
> handling capability also.
>
> John
>
>
> >
> > Haven't looked at John's page for a while.  Does the formula somehow
take
> > into
> > consideration the size of the coil?  My 6.0" diameter coil which I run
at
> > about
> > 6kva should produce about 132" sparks according to the formula.  The
best I
> > have achieved is 104".  I do believe that a 10" or 12" diameter coil
with
> > this
> > much power input could certainly produce 132" sparks.  For a given size
coil,
> > there is a maximum level of power that can be input to the system.  By
just
> > using the formula, one could expect 132" sparks with 6,000 watts input
to a
> > 3.0" diameter secondary - which I don't think is feasible.
> >
> > Sometimes I think I am on the verge of destroying my secondary at 6 kva.
> >
> > Ed Sonderman
> >
>
>
>
>