Re: Passive Ballasting for DRSSTC - My thoughts before Ed Wingates Teslathon

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Original poster: Steve Conner <steve@xxxxxxxxxxxx>



>     I think you may have found one of those points common to all 
> non-linear dynamical systems where the operation is "critically 
> dependent upon initial conditions".

Maybe. The fact that someone mentioned he got fewer cycles with the 
"ballast" in place, though the pulsewidth was the same, suggests that 
the system was mode hopping.

By mode hopping I mean: Self-resonant DRSSTCs can resonate at either 
of two frequencies (the poles or modes). In practice, the system 
resonates at whichever pole has the highest loop gain. Detuning by 
streamer capacitance will increase the gain of the lower pole if the 
coil uses secondary current feedback. With primary feedback, it 
increases the gain of the upper pole.

If the primary and secondary are tuned fairly close to each other, it 
is possible that the coil could start out oscillating at one 
frequency and then switch to the other as the burst progresses and 
detuning gets heavier.

This is the strongest source of chaos I can think of in the DRSSTC, 
and it may have something to do with how the ballast circuit 
operates. The extra impedance of the thin wire may be just enough to 
prevent a mode hop.

Steve Conner
http://www.scopeboy.com/tesla/