The total inductance measured with the solenoid coil connected to the center
winding of the flat spiral coil was 6.93mH. The frequency was measured
with a frequency generator, voltmeter, and oscilloscope at 428KHz. While
measuring the frequency I noticed many unusual wave patterns. Most of the
wave forms did not look like a sine wave at all. There would be a sudden
peak followed by a partial gradual decline and then a sudden drop to the
opposite polarity peak. It was more like a sharp pulse than a sine wave.
Total secondary capacitance was back-calculated at 19.95pF. This
included the 4" diameter copper ball seen below.
The primary capacitor is .009uFand the primary coil can be tapped from 7uH to
22uH and was tapped at 15uH for this test run. The primary capacitance and
inductance were measured.
The spark gap is an air cooled 8 point series gap with only two gaps used.
Beyond the coating on the flat spiral coil there are also to 1/4" thick
Plexiglas disks between the primary and flat spiral coils. This was found
to be necessary due to arcing through the Plexiglas. Now there is no
arcing directly between the flat spiral and primary coils.
The bottom lead of the solenoid coil is connected to the center lead of the
flat spiral coil. The outer lead of the flat spiral coil is connected to
ground.
Below is a picture of the secondary setup...
The solenoid coil was wound specifically to be 3 times the wire length of the
flat spiral coil. It wasn't clear to me before starting the winding
whether the resonance would be two separate waves or one continuous wave.
Also, my goal was to have the flat spiral be the main resonator and then
hopefully there would be 3 of the flat spiral waves in the solenoid coil.
During the calculation and tuning process, however, I decided to start with
the resonance of the total system. Before doing more exotic tests, I felt
it important to apply standard Tesla coil operating techniques to get a
benchmark. Using the above parameters and tuning for 428KHz, I got output
as seen below...
There was nothing particularly striking with the output of this
setup other than the pattern of electric jets [I incorrectly called these
streamers] from the copper ball. The electric jets were straight and occurred consistently from the same positions.
They did not dance around like streamers on a solenoid- only coil behaves. In fact, the
output of the flat spiral / solenoid combination resembled that of a plasma ball
under high pressure but without the rarefied gas effect. The electric jets
were not particularly long and varied from 2 to 4 inches.
One other interesting observation is that even though the spark
gap ran continuously, the length of the electric jet output varied. After making a few
adjustments for closer resonance the electric jets dropped back to less than an inch
in length and expanded out to 5" in length. There was no particular
rhythm to this expansion and contraction effect. It almost seemed as
though the coil was responding to the electric field in the ground connection or
surrounding atmosphere, or both.
In the section of the solenoid covered with polymer coating,
there were no corona discharges. But in the lower part of the solenoid
coil, specific
locations emitted a jet of ions and generally glowed with corona.
I was shocked (literally) to find out that a solenoid coil could
hold a substantial charge for several minutes after the coil was turned off and
even removed from the system. In one case I stroked my fingers along the
coil and received a shock about midway down. Another time I removed the
solenoid from the flat spiral to make an adjustment. The connection
between the two is via a copper alligator clip. When I touched the
alligator clip I received a shock while removing the coil. About 30
seconds later after receiving the shock and with the coil disconnected I touched
the alligator clip again and received another shock. Not being amused I
moved the alligator clip in contact with a ground wire to drain any remaining
energy. After touching the alligator clip to the ground wire for a couple
seconds I touched the clip with my hand again and received yet another
shock. All three shocks were of considerable charge.
After running the above tests, I connected a 30" flat disk
to the bottom of the flat spiral coil center lead. The rest of the coil
remained in the same configuration. The lower disk did not diminish
performance much. But there were ion leaks around the disk which did
slightly reduce the output at the copper ball. With the copper ball
removed there was still discharge in the same pattern but emanating from the
1/4" brass threaded rod. I'm going to disassemble the coil tonight
and coat the disks, copper ball and solenoid coil with another layer of polymer
coating. I'll also try to find something to use for immersing the
capacitors in oil.
When I start the coil up again tomorrow night I'll try to tune
to the resonant frequency of the flat spiral coil alone and see if I can get
four wavelengths in the combination system. [I never got around to this
experiment as I began looking into the physics involved.]
