Re: Modular Secondary

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

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Bonsoir Monsieur Luc!

>Original poster: "Luc by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<ludev-at-videotron.ca>
>
>Hi all
>
>I put this paper on the web at tis address :
> http://pages.infinit-dot-net/luc2/colapsed_coil.pdf
>It will be there for 2 weeks.
>Enjoye it !


Merci beaucoup, vous etes tres gentil!  And that's about all the
French I remember, after two years in northern Belgium I can do better
these days in Flemish ;-)

Hmmmmmm.  I don't like to carp and criticise, but . . . This paper by
K.D. Skeldon et al.  Interesting for its concept of portability, a
major plus point, and also for measurement of discharge current of
10-100mA average (though Terry's milage may certainly vary) sad for
its continued reliance on intermediate frequency transformer theory
etc.  They do give an expression for the input impedance of the coil
under cw conditions (or double-tuned intermediate frequency
transformer, IFT) which I think dates from 1943 and K.R. Sturley's
"Radio Receiver Design" volume 1, publ. John Wiley, if not earlier.
Given this paper was published last year, and received for publication
in October 99, one wonders if academia will ever wake up (says he
after 20 years in 5 universities in two countries blah blah blah yawn
snore ;-) to the fact that an impulse-driven TC is *not* an IFT.

I particularly like the comment (half way down p132, p7 in the .pdf)
that "a well-designed coil should be able to generate an output spark
length of 30cm for each kilowatt of input power" which is attributed
to anonymous www-based resources.  I'm sure that'll bring a wry smile
to John Freau's lips amongst others (I think you're currently getting
42ins/107cm for ca. 500W) as will the hit-and-miss asynch rotary gap
break rate/primary cap size design.  If you're one of those who has
built a rotary gap, you ought to read this paper just for
entertainment's sake.  When it comes to "the distribution of voltage
along the secondary coil follows the first quadrant of a sine
function" Paul Nicholson will be in stitches.

When I think what the authors of this paper might have gained via this
list I honestly don't know whether to laugh or cry, even given they
did this say three years ago.  If it had been vetted by some of those
on this list I can envisage a number of amendments might have been
recommended prior to publication.  They do manage to end up with 1,5m
arcs for 1,5kW input, which though not likely to impress anyone here
is at least something for their pains. FWIW, if you don't want to
plough through all of it, it's a 10kV 1,5kVA 50c/s trannie and a
60nF/40kV Maxwell cap-based system, a decent enough LTR design
(arrived at semi-empirically) if only they'd used a synch rotary.  The
topload is tiny though, and they don't give dimensions in the paper;
it looks a lot less than a 4" x 24".

Perhaps Richie (being possibly our northernmost correspondent in the
UK) would like to invite the authors of this paper to see a _really_
efficient coil.

Thanks to Antonio and Luc for bringing this to our attention.  One day
perhaps academia will arrive . . .

Dunckx