spark length vs. power input

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

Original poster: "Dr. Resonance by way of Terry Fritz <teslalist-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>


After several measurements of spark lengths vs. input power I've come to the
conclusion that John Freau's original equation may need some slight
correction factors.  It appears the correction is related to the dia. of the
sec. coil.

John's original equation is:

d  =  sqr p

where d = spark length in inches

             p = input power in watts

R. Scott Coppersmith's Wintesla program uses a correction factor of 1.2 for
all coils so the equation used in his program is:

d = 1.2 * sqr p

I've added a coefficient in place of the 1.2 that provides accurate outputs
and is dependent on the dia. of your sec. coil:

d = k' * sqr p

I've selected k' as the coefficient so as to not be confused with "k" which
is commonly used to describe the coefficient of coupling between primary and
secondary inductors.

The modified equation I use is:

d = k' * sqr p

where:    d = spark length in inches

                 p = input power in watts

                 k' is dependent on the dia. of the sec. coil as follows:

                 k' = 0.85 when sec. dia. is 3-10 inches (small coils)

                 k ' = 1.0 when sec. dia. is 11-16 inches (medium coils)

                 k' = 1.3 when sec. dia. is 17-20 inches (large coils)

                 k' = 1.7 when sec. dia. is 21-36 inches (very large coils)

                 k' = 2.0 when sec. dia. is 37-48 inches (super coils)


If you know the spark length required and want to find input power in watts
the equation becomes:

     p = (d/k') ^ 2


If you are working with larger coils where spark length is measured in feet:

     d =  (k' * sqr p) / 12 in./ft.  and is reduced to:  d = (k' sqr p) / 12

And for foreign countries:

     d = (k' * sqr p) * 2.54 cm./in. and is reduced to d = 2.54 * (k' * sqr
p)

     where:  d = spark length in centimeters

                   k' = correction factor as noted above

                   p = input power in inches



Perhaps Scott might wish to add this correction factor to his neat WinTesla
program.  Scott's program is also unique in that it quickly calculates the
size of power factor correction capacitor to use with NST's.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
 >
 > Okay, say I'm not interested so much in actual power consumed - what I
want
 > to know is what wattage I should be feeding into the Freau formula for
 > predicted spark lengths.  In this context, is it still volts*amps even
with
 > open circuit voltage and short circuit currents?
 >