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Improved coil and questions
I just recently improved my small 4", 12000 60ma Tesla coil, which was
previously giving off only 9" streamers. My previous coil had about 1300
turns of 28 gauge magnet wire on the 4" pipe. My primary coil was getting
extremely large and expensive, about 17 turns of 1/4 inch tubing, so I tried
to find how I could limit it. What I found was that my coil had too many
turns, and too small of a primary capacitance to have a smaller primary
coil. I ended up unwinding 2" of wire off of my secondary to get about 1100
turns, and the results were surprising! Using my normal 1 1/2" metal ball
on top I was able to strike a grounded object 12" away, which is much better
than previous attempts. My question is as follows: The small ball works
the best as a top load, but there is an extreme amount of corona from the
top windings, which I hear is bad. When I put on a tin can (with a 4" Al
foil covered ball sitting in it) there was still corona, but the discharge
was still good. When I put on my toroid (4" drain pipe covered with Al.
tape, 4" inner diameter) there is nothing. I put a break point on, a piece
of stiff wire, and there are only mini 1" bolts off the end. It seems to me
that It would be the perfect top, seeing that the others were insufficient.
Also, when I tried tapping the primary at about 5 turns there was arcing in
the secondary. Does that mean that it was a good tap and bad coupling
between the two coils? And another question: Are rotary spark gaps good to
use with neon sign transformers? If so, which variety (sync/async)? Thank
you,
-Andy