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Re: power v energy measurements, was Re: SSTC does 10 foot sparks
Original poster: "John Couture" <johncouture-at-bellsouth-dot-net>
Congratulations. You have beaten my TC spark record.
How did you measure the sparks?
What were the parameters of your coil?
You have found that the coil size makes a big difference.
You do not double the spark length if you double the joules. It is the coil
that determines how much the spark increases in length (if I understand you
This method gives a known amount of input energy for each spark at a certain
length. This is not possible with random length sparks. You can then make a
fair comparison of TC's with this method.
There is much more to consider. Do you have any suggestions for improving
this method of comparing TC's?
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Friday, June 25, 2004 8:54 AM
Subject: Re: power v energy measurements, was Re: SSTC does 10 foot sparks
> Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
> Hi John,
> My first coil (a small one) pulled 65 watts at 140VAC and produced 11 inch
> power arc at 120 BPS. Using your process:
> 1. 65 watts for one second or 65 joules in one second.
> 2. 120 sparks for one second.
> 3. 65 joules/120 sparks = 0.54 joules per spark
> 4. 11 inch arc
> 5. 20.4 inches per joule.
> Now using the JF equation: 1.7 * sqrt (65watts) = 13.7 inches. I didn't
> consider my coil all that efficient.
> I think one problem with inches per joule is this implies that if you
> the joules, you double the inches which many of us know to not be true.
> John Freau empirically derived equation suggest this is the case.
> Example: Take a TC designed for 120 BPS at some power level. Double the
> power and double the Cp to keep BPS at 120. Now the bang energy has just
> doubled but the spark has only increased by a factor of sqrt2. One could
> conclude that a large powered coil would yield a lower inches per joule
> a small powered coil would favor a larger inches per joule. The system is
> just not linear.
> Gerry R
> > Original poster: "John Couture" <johncouture-at-bellsouth-dot-net>
> > The calcs for my test were as follows.
> > 1. My coil wattmeter showed 120 watts for one second or 120 joules in
> > second.
> > 2. My coil output was 120 sparks for one second.
> > 3. This gave 120 joules/120 sparks = one joule produced one spark
> > 4. The spark was 8.25 inches long,
> > 5. This gave 8.25 inches / one joule = 8.24 inches of spark for one
> > energy input.
> > If you substitute the variables of any size or type of coil correctly
> > the math correctly as above you will find that the 8.25 inches is a
> > that is hard to beat.
> > All comments - please show your calcs as outlined 1 to 5 above so I
> > understand what you mean..
> > John Couture