setting up a spark gap oscillator

[Electroplater]

So I visited this page, with a spark gap oscillator on it.

Sawtooth Oscillator

I stuffed around a bit with it, but unless the resistor on the "base", if u could call it that, is at least a megaohm, it didn't seem to oscillate, but I could be wrong, how come?
And the model for the spark gap has a resistance? Why is this? I didn't think spark gaps would have resistance.

Is this simulation an accurate one?

 

[Papabravo]

So I visited this page, with a spark gap oscillator on it.

Sawtooth Oscillator

I stuffed around a bit with it, but unless the resistor on the "base", if u could call it that, is at least a megaohm, it didn't seem to oscillate, but I could be wrong, how come?
And the model for the spark gap has a resistance? Why is this? I didn't think spark gaps would have resistance.

Is this simulation an accurate one?

Air has a natural breakdown voltage. When the potential is high enough, an ion trail is created that allows current to flow. That current will flow as long as the potential can maintain the ion trail. This is the same process as atmospheric lightning. There are things you can do in the construction of the spark gap that will increase the probability of generating a spark.

 

[Tony Stewart]

The simulator is perfect. We just have to calibrate your understanding.

Ohm's Law says the arc current will be 2kV/ 2M = 1mA

The gap component "properties" are: Holding current: 1m
Therefore, the arc does not release until the current falls below 1mA with R>= 2M.

DIACs, SCRs & TRIACs work the same way with a holding current to shut off.

 

[Electroplater]

Ah thanks alot.

So how would you tweak the "holding current" in real life? The only parametre I know would be distance, and then that would just select the breakdown voltage.

I'm doing something with some dielectric matter and electric fields with it, (Im causing decomposition.) And I think if I had a spark gap oscillating with it, it would improve things.

<edit> or is it a matter of just keep on adding resistance till it oscillates </e>

 

[Tony Stewart]

Now a brain tease for the experts. Figure out why this spark gap oscillates with a damped sine without any inductance.

 

[Lightium]

The capacitor is charged until the voltage on the spark gap reaches breakdown.

 

[Lightium]

Spark gaps have capacitance too, but that's probably a challenge to program because it's dependent on the distance of the gap.

 

[Electroplater]

Now a brain tease for the experts. Figure out why this spark gap oscillates with a damped sine without any inductance.

View attachment 141165

Ive got no idea, all I can say is its probably useful having a retriggered lc oscillator at super high frequency, that would go into terrahertz, one possible way to do it.

 

[Tony Stewart]

Ive got no idea, all I can say is its probably useful having a retriggered lc oscillator at super high frequency, that would go into terrahertz, one possible way to do it.

... it has to do with Nyquist theory and convergence errors when the exponential rise time approaches sample step time, and this appears as ringing. The arc conduction risetime is very fast with negative resistance gas tubes or spark plugs. In LC circuits ringing occurs when the current is switched off. INCars they use ~ 50 kohm carbon wire to limit the conduction current.

 

[Electroplater]

haha, u made me think of something.

 

[Tony Stewart]

Now a brain tease for the experts. Figure out why this spark gap oscillates with a damped sine without any inductance.

View attachment 141165

Proof of my assertion. I reduced the Steptime in Falstad /10 , then changed the horizontal scale and speeded up simulation rate