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,

On 29 Nov 2002, at 11:26, Tesla list wrote:

 > 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.

AFA ground measurement goes, between two earth stakes is about all
you can do. There is no perfect ground as the ground is not a perfect
conductor.

 > 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.

You can't make a circuit available can you? Does the primary form a
tuned parallel cct drain load? If so, the lack of a beat envelope
suggests that it is being shunted by something the whole time.

 > 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

Very much so. Measurement of these things is science blended with
some creative thinking. It is possibly the most difficult device to
measure on the planet.

Regards,
Malcolm