Re: [TCML] Tuning SSTC to avoid losing oscillation when I try and draw discharge

[Steve Ward <steve.ward@xxxxxxxxx>]

Andreas,

You may want to experiment with the placement of the antenna,
bringing it closer to the tesla coil should help.  Ultimately this
design does suffer from loss of good feedback during ground arc
conditions.  If nothing else, the ground arc produces high frequency
"junk" that goes right into the antenna input and causes undesired
switching of the mosfets.  The fets seem to tolerate it OK, since the
switching is often far above resonance and so the current that can be
delivered to the inductive load stays pretty small.

This is why DRSSTCs evolved to use feedback from the primary circuit,
where ground arcs cannot give junk feedback signals.  Sadly, this
cannot really be applied to a SSTC, you cannot simply take primary
feedback because the primary itself is not resonant.

Steve

On Sat, Aug 25, 2012 at 12:05 PM, Andreas Hahn <andreas.hahn@xxxxxxxxxxx> wrote:
> I have sitting in front of me a lovingly wound Tesla coil adapted from Steve
> Ward's MicroSSTC plans, so young it hasn't even blown its first HEXFET.
>
> Sadly it's a bit shy. When I approach the breakout point with a metal object
> held in my hand, the breakout retreats back into the comfort of the metal
> from which it sprang (i.e. it stops).
>
> Thoughts on how to best give it the courage to keep oscillating and making
> high voltage despite the menacing approach of a big pair of pliers?
>
> This doesn't happen if I try and draw an arc with a small piece of metal
> mounted to an insulating rod.
>
>
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