RE: Performance Question

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

Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com> 

On the point about top load size, it's been my experience that a larger
top load than suggested by Dr. R. is better.

On my mini coil with a 1.9" x 9.5" secondary, I started with a 3" x 6"
toroid, and got 9"-10" streamers.  I switched to a 3.5" x 10.75" toroid
(5.6 times the sec diameter) and got 14" streamers.

On my big coil with a 6.25" x 28" secondary, my best performance has
been with a 7" x 30" toroid (4.8 times the sec diameter).

It's important to note that for a coil to function optimally with large
top loads, everything else must be "just right", or else the top load
will be too big and won't break out.  In particular, bang-size is
critical.  Unfortunately optimal top load size is something for which no
formula or agreed-upon guidelines exists.  One can only try something,
then try something else, and see which works best for you.

And to be fair, the definition of what constitutes an optimal top load
is ill-defined.  My definition has been that which results in the
longest single streamer.  An alternate and equally valid definition
might be one that results in numerous smaller, simultaneous streamers
without using a breakout point.  A third perspective may be guided
purely by aesthetics.  I much prefer the look of my mini coil with the
6" toroid over the 11" toroid.

Regards, Gary Lau
MA, USA



 > -----Original Message-----
 > From: Tesla list [mailto:tesla-at-pupman-dot-com]
 > Sent: Thursday, September 02, 2004 9:56 AM
 > To: tesla-at-pupman-dot-com
 > Subject: Re: Performance Question
 >
 > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
 >
 >
 > No apologies necessary.  We were all newbies at one time or another.
 >
 > Yes, there will be a gain.
 >
 > Voltage is created by V = -L dI/dt  (inductance x rate change of
current).
 >
 > The main part of this equation, inductance (L), for a sec coil is:
 >
 > r^2 * n^2 / (9a + 10b)
 >
 > In the number part, you want to keep r (coil radius) as large as
practical,
 > and, within reason, n (number of turns) as large as practical.  There
are
 > some offsets to the value of n but for many coils 1,400 turns is
almost
 > always a good number to use.
 >
 > If you wind a new coil, keep the 4.5 to 1 height to dia ratio.  With a
given
 > coil dia. then this fixes the winding length.  Divide this winding
length by
 > 1,400 and now you have the outside dia. of the guage wire to use.
Select
 > the wire OD value from a wire chart and use 200 degree C wire for
excellent
 > high freq insulation value.
 >
 > If possible, select a toroid size of 2 to 2.5 times the dia. of your
sec.
 > coil.  Up to 4.0 is used for extreme cases.  This requires more
primary cap
 > and more power but provides nice outputs.
 >
 > This will give you spectacular performance from your new coil.
 >
 >
 > Dr. Resonance
 >
 > Resonance Research Corporation
 > E11870 Shadylane Rd.
 > Baraboo   WI   53913
 >
 >  >
 >  > Apologies to the list for the newbie type question. Without going
into all
 >  > the specifics I have a static gap TC with a 4.5" secondary (5:1
ratio)
 >  > 1.440 Kva. I am considering replacing my secondary with a 10" 3:1
ratio
 >  > secondary. Per my calculations this would not make any viable
change in
 > the
 >  > output power (i.e. Spark length) ...am I correct or would there be
 > anything
 >  > to gain other than the fun of winding a new secondary?
 >  >
 >  > Thanks in advance for your advice,
 >  >
 >  > Emmett
 >  >
 >  >
 >  >
 >  >
 >