[TCML] Tesla Coil not working (probably primary/secondary/top load issue)

[Ray Whiteside <rs.whiteside@xxxxxxxxxxx>]

I apologize for what is probably the most typical topic you guys usually get
here, but after quite a bit of troubleshooting and personal research you
guys have been the best source I have found by far.

I am not going to dig up all the specs for things I don't think are
particularly important, but of course I can provide them on request.

I am in the U.S. so this is all hooked up to 120 V at 60 Hz.

This is hooked up in parallel to a set of PFC caps, in parallel with my
9kV/35mA center tapped NST, in parallel with a Terry Filter. I then have a
static spark gap hooked up in parallel. Then 8 .15 micro farad 942C caps in
series in series with my primary coil, which is all again in parallel with
the spark gap. To my understanding this is pretty standard. Along the lines
of my email earlier today my primary is a little over 9 turns of 10 AWG
wire, not copper pipe. I then have 800ft of 24 gauge magnetic wire wound
around a 3 inch diameter PVC pipe with a cap with a bolt through the top on
which I plan to mount a dual pie plate/4inch aluminum ducting top load on
it. I have not made the top load yet.

When I say "not working" I specifically mean there are no sparks coming off
of the top load that I can see in the dark. The spark gap is firing many
times a second (I assume 120 times a second) as it should be. I originally
had a problem in which I was using a tank cap that had a capacitance value
that was much, much too low, and while the spark gap was still firing the
difference when I put in the correctly sized caps was staggering.
Considering the size of my coil there is a LOT of power being put through
that spark gap. I think it is reasonable to say that given that, everything
behind the spark gap seems to be working. That leaves the capacitors, the
primary, the secondary, and the top load. Because of the difference in the
spark, it seems the capacitors are charging to a significant value, though
it is difficult for me to test what value they are actually getting to. But
then electrically, I don't know how the primary or secondary could be
"wrong" - they are just coils of wire. As was brought up in the other email
there could be losses because I am using a stranded wire (thanks Gary Lau in
particular), but would these losses be significant enough to make the coil
not spark off the top load at all? The secondary is grounded to a large
metal plate sitting on concrete in the driveway. I can go buy a copper pipe
and drive that sucker into the ground without too much trouble, but again I
find it difficult to believe this is the root of the issue.

I have a fluorescent bulb that is clearly glowing when placed around the
secondary, and is much brighter the closer it is. It is also glowing but not
nearly as bright when the coil is in operation but the primary is not hooked
up. From this I know that energy coming from at least the primary and I
would assume the secondary (because again they are merely coils of wire that
should follow very basic physical principles). Again though, no sparks at
all off the top. I have also tried tapping the primary at 4 different points
a total of about 3/4ths of a winding apart, there seemed to be little if any
difference in the bulb at these different tap points.

I have not actually built the top load yet, that is the first thing on my
list tomorrow. I have had a single aluminum pie plate bolted to the top and
hooked up to the secondary for the majority of this testing. Towards the end
I took off the pie plate so that there was only a bolt connected to the
secondary left at the top. I know this does effect the resonance value, but
again is the difference on such an order of magnitude that it would go from
not working at all to functional? And I was trying to tune the coil, but it
seemed to have no effect.


...must finish before I have to go back to school in a week. Any insight you
guys have to offer as I beat my head against my desk after another session
of fruitless google/mailing list searches is greatly appreciated. :)

-- 
Raymond Whiteside
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