Tesla Coil Measurements
This picture shows the set-up for measuring the
output of my Tesla coil, using my high
voltage probe and oscilloscope. The
10,000:1 probe was mounted on a camera tripod with an adapter made from
a piece of half inch thick polycarbonate. The probe tip is in contact
with the toroid.
This shows my first attempt at getting a measurement
of the Tesla coil output. The oscilloscope was set in single shot
mode. The variac was dialed up until the spark gap fired. The
coil's static spark gap was set with 5 gaps in place. I'm not really
sure what I've captured here. The apparent frequency of 14 MHz is
no where near the Tesla coil's calculated resonant frequency of 170 KHz.
It is also a fairly ugly wave form, suggesting that the coil is not well
tuned. The recorded peak to peak voltage is over 9,000,000 volts.
This shot was taken with 3 gaps and still seems
to be overloading the scope.
This waveform was captured with the scope in recurrent mode, 3 gaps
in the static spark gap and the grounding rod in place so that an arc was
present between it and the toroid during operation. Notice that the
peak to peak voltage is now only about 20 KV. Also, the frequency
of 185 KHz is much more reasonable.
This was the last waveform I captured. I had retuned the coil
and brought the ground rod closer. I next attempted to repeat this
without the ground rod. There was a blue flash from the polycarbonate
end piece on the high voltage probe (indicating an arc within the probe)
and input A of the scope went dead (input B still works). I don't
think I'll be doing any more Tesla coil measurements with this probe design.
I will need to pull the probe apart and check each resistor for shorts
before I risk using it again.
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