A collection of graphs, animations, and sounds, for Tesla coils at various tunings and couplings.
Animations are highly compressed GIF89a format, size roughly 240Kb, containing around 200 frames of secondary voltage and current,
along with the primary current.
The red lines on the animations indicate the maximum voltage or current achieved at each point on the coil.
Sound samples are 20k samples/sec mono 8 bit WAV files representing 2mS of the secondary base current
slowed down by a factor of 1000 to give a 2 second sample. Set your player to loop on this to hear
a 500 BPS break rate.
There is no attempt to match the modeled Q factors to a real system, therefore the decay rates in the simulations are not significant.
| Tuning and Coupling |
Incorrect tuning and overcoupling are often associated with racing arcs
and discharges from the secondary. In an attempt to understand the
effect of tuning and coupling on the secondary amplitudes, we analyse
a test coil in various states of adjustment.
We employ models of Terry Fritz's small test coil, 1176 turns of 24
awg, 4.25" diameter, 26" long, fitted with a John Freau 13"x4" toroid.
Various primary arrangements are fabricated in the model in order to
achieve the particular coupling coefficients. All have a similar self
inductance. The primary firing voltage is adjust to give the same bang
energy in all the examples. The secondary and toroid remain constant
too. The resonant frequency of the secondary is more or less constant,
varying only due to the changing primary-secondary capacitance.
| k = 0.10 | k = 0.20 | k = 0.27 | |
|---|---|---|---|
|
|
| |
| -60% | Waveforms Animation Sound Modes Gradients | ||
| -40% | Waveforms Animation Sound Modes Gradients | ||
| -20% | Waveforms Animation Sound Modes Gradients | ||
| -10% | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients |
| 0% | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients |
| +10% | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients | Waveforms Animation Sound Modes Gradients |
| +20% | Waveforms Animation Sound Modes Gradients | ||
| +50% | Waveforms Animation Sound Modes Gradients |
The percentage tuning indicates the frequency of the primary relative to the
resonant frequency of the secondary, ie a negative percentage occurs when
the primary is tuned below the secondary.
The waveforms, sounds, and animations are constructed from the first 48 modes
of the resonator, which accounts for frequencies up to 16Mhz. The mode plots
show only the lowest four.
Losses, and therefore decay rates of the beat envelope, are not realistically
accounted for.
All the models assume linear behaviour, ie no breakout. Thus for a system which
is forming streamers, the waveforms are only valid at most as far as the peak
of the first beat. At best, they are a guide to what the coil would like to do
if the topload was able to contain the resulting charge.
