RE: conical secondaries (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 16 Jun 2007 17:33:53 -0400
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: conical secondaries (fwd)

If I were to design an experiment to compare secondary geometries, I
think the most important thing would be to have all coils built to have
identical inductances.  If they did not, then you would need different
primary capacitances, and the power throughput from the NST would vary
due to that alone.  We surely don't want a variable power supply!

But let's be real.  We can talk all day long about ideal experiments,
but really, I don't believe that they're going to happen.  I think the
best we can hope for is to get reports that "I built a coil using a
15/30 NST with a pancake secondary and I get X inches of spark".  And "I
built a coil using a 15/30 with a helical secondary and I get Y inches
of spark".  Yes, a very uncontrolled and far from ideal comparison, but
I suspect that's as good as we're going to get.

So how about it - what kind of performance have folks seen with pancake
or conical coils, and with what size power supply?

I believe that it's possible to optimize a coil's performance in either
of two directions - long, thin purple sparks, or short, brighter, whiter
sparks.  I don't think the deciding factor is secondary geometry, but
rather a low BPS with big bang size (thin purple) vs. a higher BPS with
smaller bang size (brighter whiter).  But I must admit that I say this
without having any personal experimental experience or data to back it
up, and I would be interested in the experience of others is this
regard.  I have always strived for the longest sparks (OK, bragging
rights), and my long thin purple sparks are achieved with largest
possible bang size.  I've not pursued the other direction.

Regards, Gary Lau
MA, USA


> Date: Sat, 16 Jun 2007 10:39:16 -0500
> From: David Thomson <dwt@xxxxxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: conical secondaries (fwd)
> 
> Hi Gary,
> 
> Probably the best way to test my observations would be to build three
coils,
> each with the same wire length, wire gage, and same number of turns
for each
> of a flat spiral, solenoid, and conical coil.  The best cone design
would be
> a height equal to the base diameter, or nearly so.  Then it would be a
> simple matter of choosing a constant top load and variable power
supply.  I
> predict the conical coil will handle more power than either the flat
spiral
> or solenoid coils.  I doubt it would increase the spark length by
much, but
> the spark will be brighter and more robust in a conical coil than in a
> solenoid coil.  Since the specific application here is a very small
coil,
> the conical coil could make the difference between being able to see
the
> streamer or not seeing the streamer for a given coil size.
> 
> BTW, my observations are based upon the two different manifestations
of
> sparks I observed and spoke of earlier.  A flat spiral coil produces a
> thick, white arc indicating maximized current.  A solenoid coil
produces a
> thin purple spark, indicating maximized potential.
> 
> The solenoid coil is too narrow at the base to accommodate a flat
spiral
> maximized current, and a flat spiral has no height at the terminal to
> accommodate a solenoid maximized potential.  The conical coil
accommodates
> the high current and high potential both, thus allowing more power to
be
> stored in the coil per coil size.
> 
> Dave
> 
> David W. Thomson
> 
> > -----Original Message-----
> > From: Tesla list [mailto:tesla@xxxxxxxxxx]
> > Sent: Saturday, June 16, 2007 8:44 AM
> > To: tesla@xxxxxxxxxx
> > Subject: RE: conical secondaries (fwd)
> >
> >
> > ---------- Forwarded message ----------
> > Date: Sat, 16 Jun 2007 10:12:38 -0400
> > From: "Lau, Gary" <Gary.Lau@xxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: RE: conical secondaries (fwd)
> >
> > By what means are you measuring to conclude that "flat
> > spirals handle higher current" and "solenoids handle a higher
> > potential"?  I think the only measure of performance
> > differential that I would trust is comparing spark length
> > using the same power supply and VA consumption.  Do we agree
> > that spark length a suitable basis for comparison?
> >
> > Gary Lau
> > MA, USA
> >
> 
>