RE: first coil progress...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <Gary.Lau@xxxxxx>

Oh, sorry - I misread the original post.  The answer then depends a
great deal on weather or not there's a capacitor in the circuit.  If
there's no primary inductor and no capacitor, then there's no problem
with anything.  The gap will run much cooler than in actual TC
operation.

But if there IS a capacitor in parallel with the gap, but no primary
indictor, then there is indeed a problem.  The current through the
capacitor will not be inductively limited and may damage the capacitor.
But I'm still not sure that circuit Q plays any part.  I think the
hazard is over-current to the cap, not over-voltage.  How would the NST
be affected?

Concerning my belief that running a complete primary circuit with no
secondary would increase the RMS current through the cap - Terry's
simulation and response takes me by surprise!  I had always heard that
this was not a safe thing to do, and reasoned that by removing the
secondary and eliminating any quenching, the peak current remains the
same, but you just get more pri-sec trades in the same bang-interval, so
wouldn't this raise the RMS current?  Or are the gap losses so huge that
what isn't transferred to the secondary is mostly burned up in the gap?

It would make an interesting experiment to place a thermocouple on one's
cap and note the temperature rise with and without the secondary in
place.  If the "hazard" of running without a secondary is indeed just
another Tesla Coil myth, I'd like to expose it.

Regards, Gary Lau
MA, USA



> Original poster: "resonance" <resonance@xxxxxxxxxxxx>
>
>
>
> I was under the impression he was running a xmfr, spark gap, and
> capacitor without any inductor, either pri or sec.  With a very low
> inductance the Q would rise dramatically and certainly enough to blow
> any nst is short order.
>
> My intention was a warn him not to run an nst oscillator circuit
> without some load to absorb the energy thus keeping the Q to a
> reasonable value due to the inductance and reflected inductance in a
> Tesla oscillator circuit.
>
> Dr. Resonance
>
> >I agree wholeheartedly with your advice, but not the rationale.
> >
> >If one does not have a suitable load on a coil, the issue is that the
> >power drawn from the wall won't have anyplace "safe" to go.  By safe,
I
> >mean into bright, noisy, pretty sparks coming from the top load.  If
> >that power isn't going into sparks, it HAS to go somewhere else.  It
> >will for the most part be burned up in the gap (i.e. the gap will run
> >MUCH hotter), but additionally, it will heat up the capacitor, and
> >that's the gotcha.  The peak cap current will be unchanged, but the
RMS
> >current will be much higher.
> >
> >While the primary circuit Q will indeed be higher without the
presence
> >of the secondary, this won't result in the primary voltages getting
any
> >higher.  In a continuously excited (CW) coil, higher Q would result
in
> >higher voltages, but in a disruptive (spark gap) coil, each bang
rings
> >completely down to zero before the start of the next bang.  The
ringdown
> >time will be longer without the load, but the starting voltage and
> >ending voltage of each bang will be identical.
> >
> >Regards, Gary Lau
> >MA, USA
> >
> > > Original poster: "resonance" <resonance@xxxxxxxxxxxx>
> > >
> > >
> > >
> > > Never run it without a pri/sec load.  Without a load the circuit Q
> > > factor will rise to a very high value producing overpotentials
that
> > > will blow your caps and xmfr.
> > >
> > > With a load it will run a bit cooler.
> > >
> > > Dr. Resonance
> > > ----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
> > > To: <tesla@xxxxxxxxxx>
> > > Sent: Friday, September 29, 2006 11:40 PM
> > > Subject: first coil progress...
> > >
> > >
> > > >Original poster: Slurp812 <slurp812@xxxxxxxxx>
> > > >
> > > >I have a few pics of my progress so far.
> > >
> >
><http://www.flickr.com/photos/slurp812/>http://www.flickr.com/photos/sl
> >urp812/
> > > >
> > > >I also have one question. If the spark gap stays cool now,
without a
> > > >primary/secondary , can I expect much difference when I do get it
> > > >all put together?
> > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>