Hi, and thank you to everyone for your responses-
Bart, it's very interesting that our coils are so very similar.....
except for that whole, underperforming thing on my part. Let me give
you a little more info on my specs before we go on.
My first topload was a dryer-duct, covered with foil tape, type, 19
3/4" X 3"
I had arcs off of it, but from all over the place, even with a
screw/breakout point taped to it.
So for the moment, at least for consistency purposes, I'm sticking
with a 10" ss sphere with a 12 5/16" steel rod inserted into it. All
the arcs are headed relatively straight up now.
My gap is single static, quenched with a blower/motor from a
microwave. The electrodes are round, "almost flat" surfaces, 1"
across, made out of brass (old drawer pulls). I'd like to stick with a
ssg for now, but, if I feel ambitious, I do have a couple little
motors around that could probably give me at least an asrg.
Since my last email I tweaked a couple things, and I'm getting easy
24+" arcs now. I opened up the gap a little bit, but still backed off
if I got any arc on the safety gap. I also ground a mild point on the
rod sticking out of the sphere. Racing arcs were mentioned earlier,
but the only time I experienced them was very briefly while adjusting
the primary tap.
*Could you explain how one goes about determining the resonance for a
given system, so that they could know (within the proverbial
ballpark's range) as to whether they are str/ltr/R? Thanks everyone,
Neal.
Hi Neal,
Just thought I'd share my little coil with you since it's similar (4"
x 20" these days) and uses a supply voltage about 10.6kV at 200mA
(modified 12/60 NST), so similar to your power supply. I'm also
running a static gap on this coil. Early on and in the pics below I
have had some primary strikes but hardly get those any longer. In the
pics (at the link below), the coil ran with a rather tight coupling.
Some months later after these pics, I ended up catching the bottom of
the secondary on fire (bottom turns shorted). When I realized the
glowing red spots, I decided to just continue and let disaster happen
(which did). I ended up removing about 1/2" of winding which also
lowered coupling. The coil these days is painted red, but nothing
else has changed other than a slightly looser coupling. No more
problems with the sec bottom turns. This coil has also ran very long
runs (which I did mainly to verify coupling was good for it's
duration and I was curious as to how everything would do over a long
duration). I was happily surprised.
Well, I just wanted to show why I think your coil could probably do
better than it is now. BTW, the MMC is 18.8nF, so I also am running
STR with this setup. Other than maybe the gap and toroid, our coils
are probably not that different. Also, on this coil, I typically run
about 90 to 100 volt input via a variac to keep sparks out of harms way.
http://www.classictesla.com/photos/ba45/ba45.html
Take care,
Bart
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