Re: chokes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-qwest-dot-net>" <evp-at-pacbell-dot-net>

Tesla list wrote:
> 
> Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<ludev-at-videotron.ca>
> 
> Hi Ed,
> 
> When I do a tesla coil simulation in electronic workbench, for
> gap I used a voltage dependent switch in Seri with a small
> resistor, I set the "on" voltage at 10 kv and the "off" at 200 v
> but it's a poor simulation of a gap were the resistance vary with
> the current and these variation are not instantaneous because
> it's take time to ionized the gas in the gap and for the gap to
> recovering. What do you used?
> 
> Cheers,
> 
> Luc Benard

	I'm doing essentially the same thing, with two voltage-controlled
switches in parallel, with one reversed to handle negative voltages.  I
connect the "coils" to the capacitor side of the series resistor.  The
transformer is simulated by a resistor and capacitor in series with the
voltage source.  Resistor value is same as measured on real NST with an
ohmmeter, and inductance is inductance is that required to get a
reactance of the rated open-circuit voltage divided by the rated
short-circuit current.  Not good enough for working the full problem,
but I think it is pretty good for just simulating capacitor charging and
discharging.  When I set it up with approximate transformer parameters I
observe the same sort of behavior I get when I run my coil from a
variac.  By adjusting the input voltage it is possible to go from one
spark per several cycles of the AC input to many sparks per cycle, with
some voltages giving stable firing and some appearing chaotic with no
steady state pattern.

	One difficulty I get is that the simulation can give a steady-state DC
component of the output voltage and that, of course, is impossible. 
Doesn't seem to invalidate the results - guess computers can be fooled
into believing anything!

Ed