Re: Describing coils by their diameter, was Jonathon's 6" Coil (fwd)

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Date: Sun, 1 Jul 2007 11:50:32 +0800
From: Peter Terren <pterren@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Describing coils by their diameter, was Jonathon's 6" Coil (fwd)

I understand what you are saying but in reality most people who aim and get 
good performance have a height to width of around 4-5 times (say 20%) so it 
is perhaps not that variable.  In contrast I have never in my coiling 
experience been able to say my coil uses x watts to 20% accuracy. And I have 
a true KW meter. Current draw depends chaotically on load of the 
streamer/arc and the firing of ARSG's particularly. SRSG's may be more 
stable.  Sure, this can be averaged by an analog meter but it still varies 
and also makes no allowance for power factor. Put a capacitor across the 
line and suddenly your coil is a lot more efficient.  Electronic readouts 
tend to go nuts with the chaotic load.
I wonder how many coils are limited by breakdown voltage.  I suspect very 
few. It has never happened to me with sparks up to 3 times the secondary 
length on a 6x32 inch coil. Racing arc problems are fixed by altering 
coupling and primary hits are almost prevented by a second toroid.
Cheers, Peter
http://tesladownunder.com

>
> In a message dated 6/29/2007 8:11:01 A.M. US Eastern Standard Time,
> tesla@xxxxxxxxxx writes:
> Lately I see folks referring to their coils by the secondary  diameter. 
> For
> example a *6 inch coil*, or an *8 inch coil*, etc.  Then they are 
> comparing
> sparks lengths, etc, for a given size diameter.  The height of a coil  is
> extremely important.  It's really more important than the  diameter.  For
> example
> consider two coils; one is 6" x 20", the other is 6" x 32".  The 6" x  32"
> will be capable of much longer sparks because it will withstand a  much
> higher breakdown voltage, and there will be less tendency for the  sparks
> to arc to the primary.  By considering only the diameter, two people 
> could
> build a 6 inch coil, and the one with the (taller)  32" height could  say,
> "My coil
> is much better.  It gives much longer sparks".  And assuming a  good
> overall design and enough power, they would be correct.  Yet it would  not
> really be a fair comparison.  I prefer to describe the coil by
> its input power or spark length.  For example someone could say,  "This
> is my 5kW coil and it gives this certain spark length.  This could  then
> be compared with someone else's 5kW coil.  Or someone might say,
> "This is my 42" spark coil.  It uses 620 watts".  This could then  be
> compared with other coils that give 42" sparks, and the power input
> could be compared to judge the "efficiency" of the coil.  This is  not
> the engineering definition of efficiency that I'm speaking of, of  course.
>
> John