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

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

> Firstly, regarding the passive ballasting action of
> the DRSSTC, it works.

Well if it works, I can't argue. But my own personal
preference is for active current limiting. Mainly
because it was so easy to implement on the PLL driver
circuit with primary current feedback that I chose to
go with. The primary current transformer is there
already, as is logic to turn the drive on and off at
zero crossings, so it just took a couple of
comparators. I have had some trouble with
primary-secondary flashovers inducing spikes through
the CT that latch up the comparators- the coil stops
sparking for about a second.

Having said that, I use 10AWG primary wiring and
fairly thin 4mm tubing, so maybe I am getting some
"Passive limiting" too. At my 220kHz operating
frequency there will be lots of skin effect that makes
it even more resistive.

I have run the coil flat out with the current limiter
disabled and not had any trouble, even doing short
ground arcs. So "something" does limit the current I
guess.

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