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Re: Conditions for opt. loading, was: In vs. Out


From: 	Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: 	bert.hickman-at-aquila-dot-com
Sent: 	Friday, August 01, 1997 9:11 AM
To: 	Tesla List
Subject: 	Re: Conditions for opt. loading, was: In vs. Out

Tesla List wrote:
> 
> From:   Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent:   Thursday, July 31, 1997 2:43 PM
> To:     tesla-at-pupman-dot-com
> Subject:        Re: Conditions for opt. loading, was: In vs. Out
> 
> Hi John,
> 
> > From:   FutureT-at-aol-dot-com[SMTP:FutureT-at-aol-dot-com]
> > Sent:   Thursday, July 31, 1997 3:40 AM
> > To:     tesla-at-pupman-dot-com
> > Subject:    Re: Conditions for opt. loading, was: In vs. Out
> >
> > > I've found that it is critical to hit the "right" spark impedance for
> > > optimal loading to occur. This occurs (at least at modest k values)
> > >with an attached streamer that is the longest it can get before
> > > detaching. Using shorter attached sparks than the coil can produce
> > > does produce a mismatch. If you move a ground rod up to a running
> > >coil, the optimal length is easy to see in a dimmer gap discharge.
> > > Moving the rod closer than this brightens the gap up again.
> > >     I could write a book on it. Perhaps the best way is to try it
> > > single shot, then try it for the running coil. The lengths are
> > > different as you have energy stored in the discharge channel/ion
> > > cloud for the repetitive situation and I've found under this
> > > condition, optimal loading occurs with longer sparks than sshot.
> > >     It is kind of difficult to elaborate further without giving an
> > >actual demonstration (which I would dearly love to be able to do).
> >
> > > Malcolm
> >   >>
> >
> > Malcolm, All,
> >
> > Thanks,  I see exactly what you're saying now...  Have you compared
> > the quenching ability of twin coil with that of a regular coil?  I suspect
> > (based on Robert Steven's results) that a twin coil may give a more
> > optimal loading.  Maybe even a triple or quadruple coil would be better
> > as far as optimal loading, but probably not for spark length.
> >
> > Comments?
> >
> > John Freau
> 
> No I haven't but I'll take the storage scope home this weekend and
> check on the mini coil system. From the gap discharge brightness
> under various loading conditions it looks to be much the same but the
> scope will tell the true story. Judging by results the attached
> streamers are longer in the twin configuration. BTW, Bert Hickman had
> a great idea that explains why one _does_ get longer sparks in twin
> systems generally. Perhaps he'd like to explain.
> 
> Malcolm

Malcolm and all,

I'll give it a shot...

We all know there's a very non-linear relationship between coil power
level and streamer length. John has suggested that, based upon empirical
evidence, there seems to be a square-law relationship for Tesla Coils.
It becomes increasingly more difficult (i.e., takes much more power) to
significantly extend sparklength if we already _have_ significant
sparklength. This implies that if we halve the total power going into
one of the twin coils, we won't halve the streamer length coming from
that particular coil. Doubling the input power will increase streamer
length by a smaller factor - say by 1/4 or 1/3 depending on our current
power level. 

For example, a single coil operating at full power might provide 6 foot
streamers. The same coil operated at half that power might output 4
footers. A twin system, operating at the former full power level equally
shared between the two coils, might thus be expected to deliver 8 foot
connected streamers - an apparent 33% improvement over a single coil for
the same tank circuit power.  As we increase overall power levels, we
would expect to see greater apparent benefits in increased streamer
length versus a single coil. Twins appear to run "hotter" if we use 
sparklength/watt as a metric, and the apparent benefits over a single
coil improve as we increase power levels.

Safe coilin' to you!

-- Bert --