RE: TC efficiency, was Math help...

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

Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-qwest-dot-net>" <couturejh-at-worldnet.att-dot-net>



-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, July 15, 2001 1:51 PM
To: tesla-at-pupman-dot-com
Subject: Re: TC efficiency, was Math help...


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

In a message dated 7/15/01 1:47:42 PM Eastern Daylight Time,
tesla-at-pupman-dot-com
writes:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <couturejh-at-worldnet.att-dot-net>
>
>
>  John F -
>
>  A well known characteristic of Tesla coils is that the watts per foot of
>  spark increases as the TC gets larger. This means losses increase and
>  efficiency decreases as the TC is made larger. The range is about 200
watts
>  per foot of spark for small coils to 2000 watts for large coils. This is
>  based on measurements that  coilers make every day. Have you made
>  measurements that would indicate the contrary?
>
>  John Couture

John C,

I agree that the sparks per foot of spark increases as the TC gets
larger, This is seen very clearly from my equation:

   spark length inches = 1.7*sqrt input watts (wallplug)

However I do not consider this to be evidence of a decreasing
efficiency for large coils, and it has nothing to to with increased
losses.  Rather I think it suggests that it's
"natural" for coil output to follow this square law, simply
because one is ionizing a large spherical volume of air
around the coil, and also because the sparks get
not only longer, but a lot thicker in a large coil.  To measure
the true efficiency of a coil, other methods (other than
spark length per unit of input power), must be used.

John Freau

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

John -

What other methods must be used to measure the true efficiency of a Tesla
coil?

It isn't "spark length per unit of input power". It is "input power per unit
of spark length. The unit of one foot of spark length is a fixed amount that
can be used as a quantity of energy and can be used to find efficiency.
Forget about the spark characteristics in air.

Note that your or anyone else's spark length equation is not an energy
equation so cannot be used to determine efficiency. Your equation is like an
equation saying your car's 100 horsepower will give it a top speed of 150
miles per hour. This tells you nothing about the efficiency of your car.

I agree the random spark length is not a scientific or engineering method
for finding the efficiency of the Tesla coil. The controlled spark makes
more sense and should should be used. How do you measure the efficiency of
your coils?


John Couture

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