RE: Desktop Bipolar Coil

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "John H. Couture by way of Terry Fritz <teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


Gary -

Watt seconds,(energy) is  being discussed because the TC input energy is
required if Tesla coil efficiency is to be used to compared them.

The Tesla coil efficiency =  energy out/energy in.
The energy out and energy in are the true energies for a particular random
spark. These energies are not easy to determine.

Single sparks are not being considered here as coilers seldom use this
method of comparing Tesla coils. Single sparks present a different problem
compared to multiple sparks. When multiple sparks are used the problem is
trying to find how much of the input TC watt seconds belongs to that special
extra long random spark. It does not appear that this will be possible until
new methods of instrumentation are devised.

Finding an average length spark over a certain period of time would be
useful if it was possible. However, I do not believe any coiler has ever
made or could make these measurements.

Random sparks can be turned into constant length sparks by using the
controlled spark method. The output then becomes a constant energy output
that can give a coiler an overall efficiency for his coil that makes sense.
This appears to be the only option for the coiler at present.

John Couture

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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Monday, June 30, 2003 9:36 AM
To: tesla-at-pupman-dot-com
Subject: RE: Desktop Bipolar Coil


Original poster: "Lau, Gary by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<gary.lau-at-hp-dot-com>

It's not clear why "Watt-seconds" are being discussed.  The power to a coil
is measured in simple Watts.  If one was operating in a single shot mode,
the cap is charged over an interval of time for an essentially
instantaneous release, but then the power in the cap is typically measured
in Joules, a.k.a. Watt-seconds. But performance with single shot operation
won't equal that of normal operation where successive bangs propagate the
streamer length.

As to the suitability of "random TC sparks" for quantifying performance,
that simply is the nature of the beast.  Every streamer is a slightly
different length, as a multitude of variables interact over the course of
time.  It you really wanted to be accurate, you could somehow measure every
streamer over some very long time interval and perform some weighted
averaging to arrive at an average length.  But it's far easier to simply
choose the best result and identify that as the maximum result achieved.

Gary Lau
MA, USA


Original poster: "John H. Couture by way of Terry Fritz
<teslalist-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>


John F. -

This is what I mean by nonsense engineering when using random TC spark
outputs. This possibility also occurs with other engineering systems. Your
spark 36 inch length can be real, however, the exact watt second input to
produce this spark cannot be determined and the spark length should not be
compared to other spark lengths with an assumed same watt second input. Keep
in mind that the random spark length also has a random watt second input for
that particular spark. With most engineering systems random outputs can lead
to over unity energy.

For example -

7500 x .03 = 225 watts

John Freau equation -

      spark inches = 1.7 sqrt(watts)
                   = 1.7 x sqrt(225)
                   = 25.5 inch spark

John Freau 36 inch spark -

      watts = (inches/1.7)^2
            = (36/1.7)^2
            = 448 watts

      unity eff = 448/225
                = 3.96 = 396% over unity energy

It is amazing what you can do with numbers using random sparks!

This is the penalty that coilers must pay for using random TC spark lengths.
Hopefully, in the future TC spark lengths and watt second inputs will be
better defined.

John Couture

--------------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, June 28, 2003 9:18 PM
To: tesla-at-pupman-dot-com
Subject: Re: Desktop Bipolar Coil


Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<FutureT-at-aol-dot-com>

In a message dated 6/28/03 1:00:09 PM Eastern Daylight Time,
tesla-at-pupman-dot-com writes:

   >. It is my understanding the John Freau's equation for
   >spark length is only good for NSTs when the NST is modified.
   >
   >John Couture


John,

My equation is good for NST's whether they are modified or not.
One should use the measured input wattage for the calc, or at
least the PF corrected VA which should be a reasonably accurate
approach too.  Consider for example John Morawa's beautiful
15/30 NST coil which gave 40" sparks from an unmodified NST,
at 120 volts input.

John