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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>
I agree that using sparks as an output load to compare any type of
electrical device is not very useful unless you do it properly. It would
much more engineering sense to use resistive loads to compare Tesla coils.
The problem with the resistors is that they are not spectacular enough
compared to a 10 ft spark. The resistors, however, give you a fixed amount
of load to work with.
I believe that John Freau's voltage/watt formula and the similar formula
used in my computer program should be used with caution. Both formulas are
based only on limited empirical data that sometimes appears to work under
If I understand you correctly the conclusion you came to was incorrect
regarding the watts for spark length. When the wattage is doubled the spark
length increases only 1.41 times. This means that as the wattage is doubled
the spark length does not double and the "watts per ft of spark" increases.
More "watts per ft of spark" means a reduction in overall efficiency.
John F. and my voltage/watt formulas can not be used for determining TC
efficiencies because not enought information is taken into consideration. To
correctly compare Tesla coils the true input energy per spark is necessary.
The spark lengths will then give you a fair comparison. The TC with the
longer spark will be the better coil. In some tests you will have to make
certain adjustments to assure the tests are comparable. In the past some
coilers have made these tests of their coils but I have not seen these types
of test lately.
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Sunday, June 27, 2004 7:34 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,
> Sorry, I dont think Ive beaten anything because I dont believe inches per
> joule is a valid metric. If you really believe in JF's formula, then you
> will believe that you will need to 4x the power to do 2x the spark length.
> If both systems are at say 120 BPS, then the joules per bang will be 4x to
> get 2x the spark length. This leads to the obvious conclusion that the
> inches per bang energy will be lower with high power coils and highter
> low power coils. It is commonly accepted that the spark length is
> of the sqrt of power input.
> Gerry R.
> > Original poster: "John Couture" <johncouture-at-bellsouth-dot-net>
> > Gerry -
> > 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
> > that determines how much the spark increases in length (if I understand
> > correctly).
> > This method gives a known amount of input energy for each spark at a
> > length. This is not possible with random length sparks. You can then
> > fair comparison of TC's with this method.
> > There is much more to consider. Do you have any suggestions for
> > this method of comparing TC's?
> > John Couture
> > ----------------------------------------