> Original Poster: "Antonio Carlos M. de Queiroz" <acmq-at-compuland-dot-com.br>
> Malcolm Watts wrote:
> > Very simply, calculate Cself of the secondary and Cself of the extra
> > coil and add them together. That capacitance must also be added to
> > effective terminal capacitance to give the total capacitance on the
> > secondary side. Sum the two inductances, then use Ctot and the sum of
> > the inductances to determine the frequency to tune the primary to.
> This may be a reasonable approximation, but the presence of a
> significant capacitance in parallel with the secondary coil
> turns the system more complex, with three oscillatory modes
> instead of two. The expressions that I posted in the past are
> valid when the secondary capacitance is small.
I've tried it for the "cut in half" coil I mentioned and it worked
for that without a terminal. Scope tune came in about where the
equations suggested it should. Does one normally run with a
significant amount of capacitance in the secondary anyway? Perhaps
that is splitting hairs.
One thing I did find recently from building the scale CS machine
was that the significant coupling between the secondary and extra
coil affected spark performance quite noticeably (degraded it). On
doing a frequency sweep of the system I found the Q was degraded and
there were a few significant resonances. It's ironic to think Tesla
may have got better performance by placing the extra coil outside the
secondary like Golka did.
<snip - other points noted>