# 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 with
low power coils.   It is commonly accepted that the spark length is function
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
coil
> that determines how much the spark increases in length (if I understand
you
> correctly).
>
> 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?
>
> John Couture
>
> ----------------------------------------
>
>
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <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
> double
>  > 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
> and
>  > 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
> one
>  >  > 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
> joule
>  > of
>  >  > energy input.
>  >  >
>  >  > If you substitute the variables of any size or type of coil
correctly
> and
>  > do
>  >  > the math correctly as above you will find that the 8.25 inches is a
> record
>  >  > that is hard to beat.
>  >  >
>  >  > All comments -  please show your calcs as outlined 1 to 5 above so I
> will
>  >  > understand what you mean..
>  >  >
>  >  >   John Couture
>  >  >
>  >
>  >
>  >
>
>

```