Re: tesla coil grounding

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

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
 >
 >
 >