RE: TC Spark Energy

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

Original poster: "John H. Couture" <couturejh-at-mgte-dot-com> 


Malcolm -

Note that it is the energy in the spark that we are after not voltage.

Efficiency = energy out/energy in

The problem is to find the energy to produce a spark of a certain length
with a certain TC of a certain design.

John Couture

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


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, March 11, 2004 9:27 AM
To: tesla-at-pupman-dot-com
Subject: RE: TC Spark Energy


Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>

On 10 Mar 2004, at 17:00, Tesla list wrote:

  > Original poster: "John H. Couture" <couturejh-at-mgte-dot-com>
  >
  >
  > Dr. Resonance -
  >
  > As you know the topic of TC spark energy has been discussed before on
  > this List. Little progress was made because of the confusion over the
  > difference between power and energy. The TC spark energy test is very
  > simple, only an input wattmeter and tape measure are required. The
  > operation is continuous and the same as typical TC operation. Just add
  > a wattmeter at the input and measure the spark length.
  >
  > Because the operation is continuous the wattmeter (power) indicates
  > watts per second (energy). All you need is the number of sparks per
  > second to find the number of watts seconds or energy per spark. The
  > number of equal sparks per second is not an easy number to come by.
  > However, it can be determined provided the coiler adjusts the TC spark
  > output to give 120 equal spark lengths per second (for 60 Hz). The
  > spark should be horizontal and to a suitable ground.
  >
  > In my test I adjusted the variac to get a continuous wattmeter reading
  > of 120 watts or watt seconds. The sparks were adjusted until the spark
  > was continuous and of equal length at 120 sparks per second. Energy =
  > watt seconds = joules.
  >
  >     Joules per spark = 120 joules/120 sparks = 1 joule per spark
  >
  > The spark length was measured and found to be 8.5 inches. This then
  > gave me a Tesla coil rating for my Tesla coil of 8.5 inches per joule
  > of energy.
  >
  > It is obvious from the above that if the wattmeter had indicated 175
  > watts with a 10 inch continuous spark and at 90 sparks per second the
  > TC would be rated
  >
  >       175/90 = 1.94 joules per spark
  >
  >       10 inch/1.94 = 5.16 inches per joule.
  >
  > This TC would have been less efficient because it is producing less
  > spark length per joule of input energy. All very simple. So why is it
  > that coilers have seldom rated their TCs this way?

Because the length of spark per JOule is highly dependent on the coil
design. Pumping 1J into a high-C secondary is not going to give the
same sparklength as pumping 1J into a low-C one is it? Just for
starters, the output voltages will be quite different.

  > The answer is also very simple. This rating method gives low ratings
  > for large TCs,  only a couple inches per input joule. In other words
  > large TCs appear to be very inefficient. This is a problem. Any
  > comments?

I fail to see what the voltage developed by 1J into a small
capacitance vs the voltage developed by putting 1J into a large
capacitance has to do with efficiency.

?
Malcolm