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Re: TC Electrostatics (fwd)



> Date:          Sun, 5 Jan 1997 21:25:41 -0700
> From:          Tesla List <tesla-at-poodle.pupman-dot-com>
> To:            Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject:       Re: TC Electrostatics (fwd)
> Reply-to:      tesla-at-pupman-dot-com

> > Subject: Re: TC Electrostatics (fwd)
> 
> Subscriber: bert.hickman-at-aquila-dot-com Sun Jan  5 21:23:22 1997
> Date: Sun, 05 Jan 1997 12:00:46 -0800
> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Electrostatics (fwd)
> 
> Tesla List wrote:
> > 
> > Subscriber: lod-at-pacbell-dot-net Sat Jan  4 21:53:04 1997
> > Date: Sat, 04 Jan 1997 17:54:07 -0800
> > From: lod-at-pacbell-dot-net
> > To: tesla-at-pupman-dot-com
> > Subject: Re: TC Electrostatics (fwd)
> > 
> > Bert Hickman wrote:
> > [snip]
> > > > > Increasing Cp, Vg, and X, or decreasing Cs will increase Vs. However, Vs
> > > > > increases linearly with increasing Vg, but only as the square-root of
> > > > > the ratio of Cp/Cs. Large systems tend to significantly increase both Vg
> > > > > and Cp, while only moderately increasing Cs (to protect the secondary
> > > > > and prevent breakout at higher voltages). Not obvious from the simple
> > > > > equations above is that while increasing Cs may reduce output voltage,
> > > > > it may increase overall coil performance and sparklength for a variety
> > > > > of other reasons! Trying to maximize output voltage is not the whole
> > > > > story.
> > [snip]
> > > > > -- Bert --
> > 
> > Hi Bert,
> > Great analysis -- Starting with the conservation of energy is a good way
> > to arrive at a practical conclusion.
> > I am curious to know your opinions on what other parameters besides Vout
> > are important to overall coil performance.
> > 
> > -GL
> 
> Greg,
> 
> Thanks! I'll assume good pulse-rated caps and good, high-Q, construction
> techniques are a given. After looking at Robert Stephen's video, and
> reviewing the data from Chuck Curren on the Cox'es coil, I'm beginning
> to think that rotary quenching performance may not be nearly as critical
> as I once thought. Bang size and rep rate have got to be key parameters.
> In the final analysis, brute force power can overcome _lots_ of other
> system inefficiencies! :^) 

RWS-  Bert, I just have to step in here.  I appreciate that what you just 
said about brute power was said somewhat tounge-in-cheek, but there 
is also truth to that statement in many cases, hence the expression, 
"Don't use more force, just get a bigger hammer!"  There are many 
technical areas in coiling where throwing more power at the system 
will not increase streamer length output, but very definitely will 
increase smoke output!  Quenching performance, one of these technical 
areas, is critical to the successful operation of any coil.  As you 
increase power levels, as you are well aware, quenching becomes more difficult
to accomplish.  Quenching is certainly one stumbleblock where 
throwing more power at the problem will absolutely not increase 
output, and rather the opposite occurs in practice.  You may not be aware 
that my rotary system in MTC is now on its third differently configured rotating
wheel, and the stationary contacts are now about 4th generation.  All parameters 
including break rate, contact dwell, electrode material and air flow 
have undergone laborious fine tuning.  It now quenches 
so superbly that I do not require the crutch solution of additional 
series quench gaps and their associated introduced gap losses.

I consider the actual efficiency of my MTC system to be right up there with the 
best.  This two coil classical system achieves or exceeds the same streamer
lengths at 7 kVa that Hull's group is achieving with their highly engineered,
sophisticated magnifiers!  At just 2.5 kVa my MTC produces 6-7 foot measured
streamers if I downsize the topload to allow breakout at this more commonly
experienced coiler  power level, and reduce my system cap to just 0.05 mfd
instead of 0.12 mfd.  No bigger hammer anywhere here at all,  just highly
efficient, synergistic design.  Its a case of making a lumped parameter system 
outa just the right type of lumps. : )

> Another big factor would have to be sizing the ROC of the top terminal
> and E-field control so that it does not break out prematurely, and that
> streamers don't preferentially strike downward to the primary. Certainly
> the length of the secondary is also a significant factor - it must be
> long enough to provide adequate physical seperation between the toroid
> and the primary as well as to itself on a 2-coil system. Larger
> diameter, squatter coils might otherwise be better performers with their
> higher L versus C ratio. Electromagnetic coupling between
> primary:secondary should be as tight as insulation will withstand - and
> probably close to a "magic" value to reduce energy-stranding in the
> primary circuit. I'd really like to see if 0.28 could be achieved on a
> 2-coil system! A low-impedance path between the coil base and the other
> "plate" of the secondary's capacitance is a significant factor, more-so
> with lower Zo coils.

> Coil Zo itself is a poser! Obviously using too fine a wire gauge can
> hurt performance, but a lot has to do with whether its direct driven
> (no-one will dispute RH's results using a 30 Gauge resonator!), and the
> degree to which the coil is behaving as a distributed transmission line
> or a lumped LC.  Results on your big coil, and Cox's Milwaukee Museum
> coil seem to indicate that heavy topload C is not an automatic
> prerequisite for great performance!! 

RWS-  Bert, see my post today on topload size.

BTW, do you have any conclusions
> from the Zo/coil performance information you were gathering last year?
> 
> Still lots of mysteries in coiling, Greg!
> 
> Safe coiling to you!
> 
> -- Bert --

Lots of mysteries and generalizations for sure, but we seem to be 
narrowing and fine tuning this all down thanks to the excellent work 
of a growing number of knowledgeable coilers such as yourself sharing their
ideas and experiences on this forum, and the tremendous benefit that the
existence of this forum provides thanks to a very tirelessly dedicated Chip
Atkinson.  Keep up the good work, all!

rwstephens