Latest test results

cc: tesla-at-grendel.objinc-dot-com


Well, I had an interesting and expensive weekend.  I got the new 33" toroid
completed and the new ground rod driven in and connected.  I test fired the
new toroid with  two12kv 30ma transformers.  With one tank cap it tunes at 13
turns on the primary and I get about 29" strikes.  You are right here, I got
longer strikes with the smaller discharger at this power level.  I tried two
tank caps in parallel and the spark gap would not fire until the variac was
at full power (and sometimes not at all).  The best tune was 9.5 turns on the
primary.  Why does the spark gap not want to fire with more capacitance in
the circuit?

Next I hooked up my large transformer 12kv 120ma with the large toroid and
one tank capacitor.  The best tune I got was at 13 turns.  I gradually
increased the power and got up just over 3/4 on the variac.  Things were
going well, we had massive discharges and then the secondaries shorted on the
transformer and everything came to a quick halt.  This is the transformer
that I had chisled out of the tar and "saved".  I built a clear acrylic box
to mount it in so I saw the arcing in the secondaries.  It looks like they
arced to the core.  I think it is now a boat anchor.

Undeterred, I hooked up all the remaining transformers I had.  Four 12kv 30ma
transformers for 1.4kva.  At this power level I found the old 14" discharger
tuned at 12 turns and the new 33" toroid tuned at 13 turns.  Why does the
tune seem to change with increased power levels?  I did not expect this.  The
good news is I got massive discharges - hitting the overhead furnace ducts in
the ceiling, the adjacent cement wall, the floor and all the strike shields.
 I measured one discharge at 50".  I was amazed by the show.  With the large
toroid, the discharges left mainly in 2 or 3 places.  With the small toroid,
there was many more discharges - literally going everywhere.

After running at full power for about 10 minutes (approximately 1.0 minute at
a time with several minutes off in between) all of a sudden, everything shut
down.  After investigating I found the main tank capacitor was shorted.
 Applying a small amount of power made a kind of cliking noise inside the
cap.  Watching the capacitor revealed a steady stream of air bubbles with a
black sooty material floating to the top.  At least I did not have a fire or
an explosion.  I connected the other tank capacitor up and everything still
works fine.  I am concerned now to even run the system at full power.  I am
only at 1.4kva, which is still quite a ways short of the 2.0kva that I wanted
to get to.  I would like to take the destroyed cap apart and do an autopsy
(that will be an oily mess).  I did a good careful job building these,
cutting the poly extra wide.  I am guessing it punctured the poly somewhere.
 I was sure both capacitors were sufficiently broken in.  I have been running
them at 12kv 60ma for over a week and have seen no air bubbles come up.

I noticed in reading the KeelyNet capacitor file (CAPACITR.ASC) that he
says.0625 poly is only good for 7500 volts AC and for up to 1500 volts AC I
need .090 poly.  Do I need to build two new capacitors with .090 material?
 This project is getting quite expensive.  As my wife reminded me yesterday,
I have already invested a small fortune over the last two months.  If I need
to build new capacitors it will be a while.  I also need to find more

It seems that for any combination of discharger and input power, maximum
output power is obtained with whatever tank capacitors will tune at 13 or 14
turns of the primary.  i.e. using all of the primary turns is much more
important than the amount of tank circuit capacitance.  Do you agree?

Ed Sonderman