Dual toroid and efficiency tests


Lately, I've been running my "42 spark TC" at 950 watts instead of 
560 watts.  At 950 watts it gives 49" max sparks with a 4" by 13"
spun aluminum toroid.  Sparks can reach 49" with or without a toroid
breakout bump, but they reach 49" more consistently with a bump.
(all power measurements with lab type wattmeter....wallplug power)

When Barry Benson visited recently, he suggested placing a 3" by10"
toroid beneath the larger toroid.  I finally got around to trying that, and
my spark length increased to 58" max at the same 950 watts input.
There is 1/2" space between the toroids, this helps to increase the
capacitance, and besides, I don't want to mar the finish of the toroids
by letting them rub together.  These latest results obey the square
law for spark length that I use for my coils:  

 max. spark length (inches) = 1.9*SQRT input power (wallplug watts)

Without a bump, the sparks emit mostly from two spots on the toroid,
but occasionally just from one spot.  The sparks are about the same
length whether I use a breakout bump or not.  So basically, I get
what appears during operation to be multiple streamers that break
out in all directions, and reach full length at times.  It is possible that
the multiple steamers are actually forming sequentially, but too fast
for the eye to separate in time.

Here's some conclusions and observations:  Much of this has already
been reported by others on this list in the past, so it's more of a
verification, with a heathy dose of speculations thrown in.

1.  Smooth toroids seem capable of producing longer sparks than
     corregated toroids either with or without a breakout bump.  This
     might become less important with really large toroids?

2.  Corregated toroids often seem to need a bump for longest sparks
     unless the toroid is large enough to give just one streamer.

3.  A corregated toroid may need to be 50% to 100% larger than a
     smooth toroid for the same spark length.

4.  Adding the second toroid made it easier to obtain just one streamer,
     (probably due to the lower voltage), and the sparks got much longer.

5.  Sparks no longer strike the primary, but they hit the ceiling more

6.  I had to tune one turn out with the extra toroid added.

7.  A proper correlation between ROC and voltage may be quite

8.  As a toroid becomes larger, the corregations may have less effect
     because they may be a smaller percentage of the total toroid size.
     This might come into effect with toroids that are larger than 35" or
     so (just guessing).

9.  When the smooth toroid gives multiple streamers, sometimes they
     might not all be there at the same time; they may be forming
     sequentially, but the eye's slow frame-rate sees them as existing
     simultaneously.  In contrast, corregated toroids may be more likely
     to form actual simultaneous streamers resulting in shorter sparks.

(I now manufacture high quality spun aluminum toroids.  To order a
4" by 13" toroid, send $126 postpaid to:  John Freau, 49 Thiem Ave, 
Rochelle Pk, NJ   07662)  These can be seen at my website at:

            <  http://members.aol-dot-com/FutureT/index.html  >

(photos are a little blurry due to cheap digital camera)

(1.5" by 6" toroids are also available for $32 postpaid.  These are good
for small coils, or as corona shields, etc.)

John Freau