Re: tesla coil grounding

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "george hadle by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ckreol1-at-yahoo-dot-com>

malcolm, thanks.  It's not in cw mode, but damped,
which is why I expected to see some decaying waveform
at least slightly varied from the normal rlc decay.  I
added a ground today  (how do you measure the ohms of
a ground?)  copper pipe, wet ground, 3 feet.
Yeah, direct scope connection halved res. freq of
secondary.
helical primary 8 inch diameter
secondary 2 feet tall 4 inch diameter
scope lead picks up radiation.
Its a square wave.  Perhaps my circuit is wrong.  cap
and primary in parallel.  mosfet nearest the the dc
power source.  It pulses the lc circuit.
Also a note about self capacitance of a coil.  It
decreases the horizontal (time) length of the ringdown
waveform.  This can be seen by bringing you hand near
your coil and watching it on scope.  Hand=capacitance
Thanks for helping out a new to tesla coil-er.
--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Malcolm Watts by way of Terry
 > Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>
 >
 > Hi George,
 >             I take it from your description that the
 > coil is
 > effectively being run in CW mode. An energy transfer
 > is indeed taking
 > place - but it's a continuous one from primary to
 > secondary unlike a
 > cap discharge system which gives the energy exchange
 > waveforms you
 > seem to be expecting. Connecting the scope directly
 > to the secondary
 > is not a good idea, either from low-powered
 > measurement or high-
 > powered scope survival points of view. In the former
 > case, the
 > scope's probe capacitance and shunt resistance will
 > throw the
 > measurement results off by a country mile for a
 > small machine.
 >
 > Regards,
 > Malcolm
 >
 >
 > On 26 Nov 2002, at 21:14, Tesla list wrote:
 >
 >  > Original poster: "george hadle by way of Terry
 > Fritz
 > <twftesla-at-qwest-dot-net>" <ckreol1-at-yahoo-dot-com>
 >  >
 >  > several questions.
 >  > I have a mosfet driven (protected and enhanced by
 >  > schottky 1206d 's) primary coil of about twenty
 > turns
 >  > of 22 gauge bare copper wire.  A secondary with
 > fres
 >  > of 333 khz.  I have a small heat sink on the fet
 > which
 >  > gets hot; several watts.  when conncting scope
 > leads
 >  > (inductively and directly) to the secondary it is
 > a
 >  > standard rlc ringdown w.f. It is tuned pretty
 >  > precisely. I want to know if the fact that its
 > not
 >  > grounded preventing the existence of an rf
 > envelope
 >  > looking w.f.  I tried varying the coupling.  Why
 > no
 >  > energy exchange between pri and sec??  It's
 > driven by
 >  > a cmos sq wave oscillator.  I know I need to get
 >  > higher current to charge the  fet quickly
 >  > thanks
 >  > george
 >  >
 >