Re: Tesla Coil toroid Size

To: tesla-at-pupman-dot-com
Subject: Re: Tesla Coil toroid Size
From: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz> (by way of Terry Fritz <terryf-at-verinet-dot-com>)
Date: Thu, 17 Sep 1998 15:02:28 -0600
Approved: terryf-at-verinet-dot-com

> Original Poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net> 
> 
> 
>   Malcolm -
> 
>   Can you show your calculations using my RMS numbers and your
> instantaneous numbers to arrive at your conclusions?
> 
>   John Couture
> -------------------------

Be happy to.
You wrote:

> > 
> >>   For example if the input is 960 watts and the bks are 120 and the
sparks
> >> are 2 feet long then the TC is producing 8 watts per break (including
> >> losses) and four watts per foot of spark. 

960W = 120/s * 8J

Remember that J = W-s 

An example:
I have observed energy disappearing in one coil in just 25uS. Let us 
be really generous and say 50uS. Since 120/s = a period of 8.3333mS
from start of one gap fire to start of the next ,the coil is 
exhibiting a duty cycle = 0.000050/0.008333 = 0.006 or just 0.6%
That 8J is disappearing in the output discharge and gap during the 
50uS so the peak power equivalent =  8J/50uS = 160kW  The shorter the 
time period during which the energy is dissipated, the higher the 
peak power in the coil.

     Note that there is a very considerable quiet period of (0.008333 
- 0.000050)s = 0.008283s  or if you like, 8.283mS between gap fires 
or "bangs" as I define them. 

BTW, the dissipation time is not guesswork. Anybody using a storage 
scope can capture these waveforms and measure them to within a couple 
of microseconds at worst. I think nobody here would doubt that 
remaining ringing at a few percent of initial amplitude is not 
significant, remembering that energy at the peak of oscillation is 
proportional to V^2 and a drop of just 30% represents a 50% energy 
loss. Visit Greg Leyh's site for scope pictures of a really high 
powered system (you have haven't you??). Look at the scope photos I 
indirectly provided you with of a sparking coil. Better still, get a 
scope and *measure it*.

Malcolm

> >By that logic, one can produce a 100 foot spark using 1W. In fact the 
> >TC is discharging 8 *Joules* per break. The low duty cycle turns that 
> >energy in the attendant period of time into kW if not MW pulses.
<snip>