From: "Terrell W. Fritz"
Date: Thu, 07 Dec 2000 19:24:32 -0700
Subject: Re: [TSSP] E-Tesla6.11
Hi Paul,
At 09:37 AM 12/7/2000 +0000, you wrote:
>I wrote:
>> > Terry, you recall I expressed some doubts about the method
>> > applied in E-Tesla6 - I felt that it might not be representing
>> > the energy stored in the internal capacitance. Computers here
>> > have been churning through telescope data, so I've had time to
>> > sit back and work through the math and I'm quite certain now that
>> > your method is correct, providing that is, you calculate Fres by
>> > resonating your C with the right inductance. The required
>> > inductance is the equivalent series inductance (Les), formed by
>> > integrating the EMF induced along the coil,
>
>> > Les = integral{ x,y = base to top, M(x,y) * I(y) * dx * dy}/Ibase.
>
>Terry wrote:
>
>> Oh good! The capacitance should have been right.
>> You had me worried ;-))
>
>Yes, sorry about that! Some time ago now, when I first came across
>E-Tesla, I wrote saying that I thought you should be calculating
>the V profile rather than just assuming it. Having since gone to
>the trouble of doing just that, I can appreciate now that assuming
>the profile is a reasonable thing to do in order to arrive at a
>practical program.
The program is not terribly sensitive to the profile as long as it is close
or part of the set of odd profiles that magically give the "right answers".
> also thought that you would not be able to
>fully capture the effect of the coil capacitance with just a single
>surrounding gaussian surface, thus ignoring internal stresses.
I guess Gauss was right about that ;-)
>
>Having learnt a few things since then, and thought it through more
>deeply, I'm beginning to think that you've got a nice compromise
>with E-Tesla. OK, you're also having to 'guess' the effect of the
>current profile by introducing an Lfac, which includes a hidden
>guestimate of the internal capacitance by way of its effect on the
>current profile. Thus, on the face of it, you're still having to
>guess two out of three reactance distributions. Having said that,
>the one which you are calculating - the external C, is surely the
>one to go for, since this is the one most affected by the coil
>surroundings. The other two - internal C and mutual inductance -
>are related to the coil size, turns, and h/d, but less dependent
>on the exterior geometry and so these ought to lend themselves to
>being determined by some formula mapping h/d to an Lfac. For that
>reason I'm beginning to think that E-Tesla is applying the right
>kind of effort in the right place to achieve a practical result.
I always gauged the program against the "does it really work" standard. It
always worked very well and it was just a matter of getting it more
accurate and faster, faster, faster... I used to set my alarm clock for
3:30 AM to get up and pump the next set of test values into it in a long
two day marathon. I can now do that some thing inside of an hour...
I tried to avoid "fudge"factors but was always ready to use them with wild
abandon if needed ;-)) We really needed a program that simply "worked" no
matter what the method.
When I started E-Tesla (TWFTesla back then) there was "nothing". If you
wanted to guess a secondary system frequency, you had to add the standalone
torroid capacitance to the self C of the coil along with a magic factor
that nobody knew. Taking into account the geometry of the rest of the
coil's components was a joke... E-Tesla really broke the barrier of
mystery that surrounded the secondary fields and frequency calculation. I
am truly thrilled that now new tools like yours have taking this art to
such a fine detail. It was only a two years ago when such things we deemed
impossible by many and now it seems like we have been doing such
calculations for 50 years without a second thought ;-)) It is a little
scarry that your project showed such a dramatic error in the secondary
profile in the 5 version of the program but reassuring that the results
were simply made even more accurate when the error was corrected. I have
done a lot of finite element work and I guess I was in the right place at
the right time...
E-Tesla has gone through a lot of twists and turns so it should be on the
right track as far as methodology goes. Someday soon, there will be some
polished GUI version based of the basic code but the projects only purpose
was to break into the area and provide the basic structure for future
programs. That effort has well exceeded my goals of the time wildly.
I am awe struck at program like yours that rip through the same types of
ideas with a totally different perspective. "I" could not have ever
figured such a thing out, but it is wonderful to see new and powerful
methods arrive on the scene. Some times I mull over old Tesla list posts
from 5 years ago and laugh at all the things we thought to be true such a
short time ago. I have always been into coiling to sort of "slap things
around" and clean up this hobby. It has been 100 years now and not
knowing the secondary voltage profile and other basic things has always
struck me as ridiculous. We put a man on the moon over 30 years ago so we
should be able to figure out the voltage of a large aluminum toroid 5 feet
in front of us now...
One little aspect "I" really will enjoy about the secondary profile thing,
is that it was accurately predicted by computer modeling BEFORE that
profile was demonstrated by measurement! I used to be prodded by the "seat
of the pants" coilers who ridiculed people whose coils were made of
electrostatic charges in little silicon gates made by Intel. So I get a
always get a little thrill now poking them boys back ;-))
>
>I wrote:
>
>> > I'll endeavour to produce a document which defines all these
>> > 'equivalent self capacitances' and shows how each is related
>> > to the physical capacitance distribution, and to each other.
>
>It's well on the way - the first 18 pages are done. This is a new
>doc which will replace the hurriedly written pn1310 and pn1710 and
>which goes into things in much more detail, but hopefully with a
>more accessible exposition.
WOW! That's great! As all this breaks new ground we really need some new
definitions and a new "dictionary" to guide us. The old "Cself" now has
all kinds of meanings to all kinds of people. We no longer know exactly
what terms mean what. Your work here will probably define the art for
decades to come. So don't screw up! :-)))))
Cheers,
Terry
>
>Cheers,
>--
>Paul Nicholson,
>Manchester, UK.
>--
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.