Re: 20 joules at 100 bps vs 4 joules at 500 bps - any difference?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: FutureT@xxxxxxx 

In a message dated 7/13/05 5:01:03 PM Eastern Daylight Time, 
tesla@xxxxxxxxxx writes:


> John's equation there is for NST powered coils at 120BPS only.  We are
> trying to extend it to other coils and BPS rates too.


Terry, all,

My equation was never intended to be limited to NST's nor
to 120 bps.  But for small coils it works best at 100 or 120 bps.

When I designed my equation, I looked at the performance
of various coils such as Richard Hull's Nemesis coil, Greg
Leyh's large coil, and my own coils which were powered
by NST's in some cases and by potential transformers in
other cases.  I noticed that the square root function
related the power input to the spark lengths for all these coils.
I selected a suitable coefficient (1.7) so I could directly relate
input power to output spark length.  In those days folks had
been using a linear spark length measurement such as
500 watts per foot of spark length.  I was looking for something
that worked better and came up with my formula.  Hull's nemesis
coil ran at about 300 to 450 bps, and Greg's coil ran up to 300 bps
or so.  I also looked at some larger coils that ran at 240 bps.
My coils also functioned over a wide range of breakrates,
but I found that I needed the low 120 bps efficient breakrate
to get the formula to work for small coils.  This led me to
conclude that the formula doesn't "track" precisely for both
large and small coils, but it was good enough for a lot of everyday
non-precision coiling work.  What I mean is that a real small
coil will do worse than the formula predicts for 120 bps, and
a large coil may do better than the formula at 120 bps.
I considered the formula to be useful up to 400 bps
or so especially for larger coils.  I used to include all these types
of comments in my earlier postings but I got tired of repeating
it all eventually.  The formula was intended to be a rough guide
of how much spark length could be achieved for a given input
power.

In my work I found that higher
breakrates can definitely add considerable length to the spark
lengths but the results seem to vary from coil to coil.  This
assumes a steady bang size and simply ramping up the
breakrate.  Of course the 120 bps is still more efficient.
A lot of the bps increase does go into making the spark
brighter as the DRSSC work has also shown.  My early work
certainly showed the advantage of a big bang.

I did some work with various formulas that would allow for
differences in breakrate, but I didn't continue much with that.

Cheers,
John