On 16:59, Charles Van Neste wrote:
Hi Everyone,
I have been trying to quantify the Tesla coil I recently made and
I've had some issues trying to calculate the voltage of the top
terminal (I think it is normally called the Top load - but I think
that is a terrible description). Anyway, measuring the E field is
straight forward. I typically put mini-grabber clips on a pole and
elevate it to the same
height of the top terminal. The clips are connected to a coax cable
which goes to a grounded oscilloscope - making sure this E-field
"probe" is far enough away not to disturb the system. Of course the
E field is not the actual voltage of the top terminal. The only way
I've been able to estimate it is to slowly turn the input voltage up
until streamers form at the top (then I know the top terminal voltage
is near 30kV - since that is the breakdown voltage in air, again this
still assumes a gap of 1cm and the top terminal is with respect to
ground so the voltage may be much higher than 30kV)
This can be wrong by an order of magnitude. 30 kV would cause
breakdown in air in a sphere with 1 cm of radius, not on a large toroid.
. You can't bring a probe near the terminal or you change
everything. I need to know the top voltage so I can get an accurate
measurement of the voltage gain of the system (from input to output -
output being the top terminal). I would think there is a way to
calculate the voltage by taking measurements of the E-field (since
voltage should be related to the electric field)? How do you guys
figure out your top terminal voltage?
Connect a signal generator between the top terminal and ground with
known amplitude, as large as possible, and frequency close to the
resonance frequency of the secondary coil. See then what the
oscilloscope measures. You have then the ratio between actual terminal
voltage and the measurement, that shall be the same with the coil in
operation, before streamers form at least.
Antonio Carlos M. de Queiroz
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