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Re: Thyristor driven coil ??



Original poster: Greg Leyh <lod@xxxxxxxxxxx>

Two performance parameters for thyristors limit their use in Tesla Coil work; the dI/dt rating and the recovery time, or 'off-time' as called by some mfrs.

Most garage-scale coils have primary waveforms with dI/dt slopes of several kA/us. Only the 'interdigitated gate' thyristors can handle such a slope.
More critical is the thyristor recovery time; the period after conduction before the device can once again support its rated voltage.
Typ times are 100's of usec, where considerably shorter times [10's of usec] are needed to properly quench.


-GL

Original poster: "James Robinson" <james.robinson@xxxxxxxxx>

Hi, just a speculative thought - has anyone ever tried (or would it work) to use high power thyristors to replace the spark gap in a standard TC? I have seen modern "puck" thyristors capable of switching over 2kA at over 8kV continuously and dV/dt ratings of several thousand V/us. I may be missing a vital point here - other that the extorsionate cost of the things!)? One such problem might be the leakage current making it very hard to get the tank cap to charge.

It would have to be a BIG coil I suspect to get the resonant frequency down as much as possible (a few 10s of kHz) thus reducing the dV/dt enough.

just a thought...

James R