Re: A figure of merit

To: tesla-at-pupman-dot-com
Subject: Re: A figure of merit
From: "David Trimmell" <davidt-at-pond-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Fri, 28 Apr 2000 12:26:15 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme
Hi, I find this kind of amusing. A rating of power in (true watts) vs
spark output length makes good sense for a "clasic" TC (with sub
catagories of spark luminosity ;-)). This can also work for TC hybrids, as
Solid state and Vacuum Tube coils. Seems fare to me. Why complicate it? As
far as marit for Low voltage vs high voltage primaries, again there are
tradeoffs, low voltage means more amps, larger wires, etc.,and high
voltage means lower current, smaller wires, more insulation/spacing. I
wouldn't recommend feeling "a whole lot more comfortable" around low
voltage (high current) primaries over HV primaries, they can both kill
you. Of course, the issue continues to cloud with Vac and Solid State
coils: Steady CW? (how big is your flame, Baby!) Pulsed? How many stots
per second? I agree with the idea that beauty is in the eye of the
beholder ;-) I like my 5 inch flame at 85 db!

Regards,

David Trimmell


On Thu, 27 Apr 2000, Tesla List wrote:

> Original Poster: "Kennan C Herrick" <kcha1-at-juno-dot-com> 
> 
> Marco & Luc have good points re a better figure to use.  But it would
> need to be decided as to what properly constitutes "merit".  Part of
> "merit", I think, is how far removed one can contrive to get from
> becoming inadvertently fried.  That's why I chose primary volts: my 160 V
> DC is a whole lot more comfortable to be around than others' 10,000 V, 60
> (or 50) Hz AC.  But it is more logical of course, from the purely
> mechanistic standpoint, to use ampere-turns, ampere-turns being the
> determinant of the magnetic flux that is generated, which is all that the
> secondary "sees".
> 
> Seems to me we might want a figure a) directly proportional to spark
> length (of course), b) inversely proportional to primary ampere-turns and
> c) inversely proportional to primary voltage.  That is, longer spark =
> good; more primary ampere-turns = bad; higher primary voltage = bad.
> 
> For any given quantity of primary turns, the amperes will be proportional
> to the volts.  Thus an equation that would satisfy the criteria would be
> M (for "merit") = L {in mm}/(V {primary volts} x N {# of primary turns}).
> 
> For my present coil, I come up with--surprise!--the same 3.8.
> 
> Over...
> 
> Ken Herrick
> responding to:
> > Original Poster: "Marco Denicolai" <Marco.Denicolai-at-tellabs.fi> 
> > Original Poster: "Luc" <ludev-at-videotron.ca>
> > snipped<
> > Herrick's original msg:
> > >A while back Gary Johnson asked for reports on solid-state spark 
> >> length; and I responded with a proposal for a figure of merit or
> "quality"
> > >measure for Tesla coils: spark length to a grounded point per primary
> > >volt--for all builders, solid state and "spark".  I proposed
> millimeters
> > >per volt just to make the number less depressing (25.4 mm are in 
> > each and every inch!).
> 
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