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Re: Tesla coil specs.

Malcom requested:

>
>Bert, would you mind posting your secondary stats (again I guess)
>and the resonant frequencies for each of the three coil/toroid
>combinations. In the light of some work I did on secondaries last 
>year plus some other information people have posted to the list, I
>am keen to know what capacitance/wirelength combination you scored
>best with and with what frequency. Also the winding height and 
>diameter. As many stats as  poss. I think this could be very 
>interesting.
>
>Regards,
>Malcolm
>
>

Malcom, I did not have a frequency counter, signal generator or a decent
scope at the time I first used this coil/toroid arrangement.  I simply put a
toroid on top and put a .0125 ufd cap in the circuit and tuned the primary
for max output.  I then went to the larger toroid and did the same, and then
used both toroids together for max top capacitance.  I then threw a second
cap across the first and repeated the process.  Best performance was with
the 32 inch toroid by itself with 3 caps.

But the specs on the secondary are:
Sonotube form, 10.5 inches diameter (Yeah, I know, but it was an early coil)
Wire: 15 gauge enamel  (No one ever sees 15 gauge wire, but hey, it was cheap)
Winding length, 21 inches, tight wound, 3 coats of polyurathane

Toroids: 24 inch outer diameter, 7 inch chord
         32 inch outer diameter, 7 inch chord
         Both stacked

6 neon transformers, 9 kv, 60 mil each, paralleled.  I used four ferrite
toroid cores wound with about 20 turns of wire along with two .005 bypass
caps with a safety gap for transformer protection.  Chokes and caps were
arranged in a double pi section filter arrangement.  I ended up using a
rotary with no static gaps.

Caps were Hull type, 0.060 mil, about 0.0125 ufd each.  I eventually blew
all six, and that's just on 9 kv input (ok, I admit my variac was wired for
overvoltage, so the transformers probably went up to maybe 12 kv).

Output averaged 4 foot sparks, with a couple of 60 inch strikes recorded on
video.  I have some neat footage of my step-son taking 3 foot strikes to a
wrench in his hand while 4 inch sparks shoot out of his knees and sneakers!
(He was isolated from ground while crouched on a large plastic box).  And I
got some closeup shots of lightning shooting out of his toe nails.  Cool.  I
keep saying I'm going to send Richard Hull copies of this tape to include on
one of his tapes.... maybe this fall.

Anyway, this coil has been my favorite so far.  

My last coil was finished January '95.  Secondary is 16 inches in diameter,
4 foot coil length, teflon insulated stranded wire, 22 gauge (about 3,000
ft).  Primary is a 4 foot diameter flat spiral monster using 1+ inch
diameter coax.  Toroid is 62 inch diameter, 7 inch chord. I got a very
disappointing 6 foot discharge with a 15 kva pole pig, 14.4 kv.  I'm
rewinding the secondary with 10 gauge enamel, and will try it again with
better caps (last time I used some questionable pulse discharge caps which
were very lossy at Tesla coil freqs).  Caps which are rated at 800 pulses
per second just don't work well when you use them in a resonant circuit at
approx. 100 khz or less!

Bert