Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Hi Terry,
Tesla list wrote:
Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
Hi Bart,
I was going to put the cone formula in but I got worried from this post:
http://www.pupman.com/listarchives/2001/January/msg00418.html
yes, exactly! The error was unacceptable from a programming
standpoint (meaning, when the error gets too high, "what's the
point" in programming. This is why I started working with the
equation in the first place.
It sounded like there was some question as to if the formula was
valid. Has you tested it against Paul or Mark's programs?? If so,
then I will put it in. If not, then maybe it needs to be
checked? I added it anyway....
I see you put in the "original" formula?. Ahh, my fault, I didn't
include my factor in the puzzle. Geeze, I hate when I do that!
Sorry, here it is:
My factor is 1/SQRT(sin(x)+cos(x)) and the whole beast should look like this:
L = SQRT[(L1*Sin(X))^2 + (L2*cos(X))^2] x [1/SQRT(sin(x)+cos(x))]
The difference is, well, let me show you with an 8"ID, 32"OD flat
coil using .25" tubing at 24 turns.
I'll raise the outer height up in 5 degree increments maintaining 24 turns.
Goetc-L Orig-L Orig-err Bart-L Bart-err Angle OD
---------------------------------------------------------------------
270.6 271.7 0.40% 271.7 0.40% 0 32
269.6 274.9 1.93% 264.1 2.04% 5 31.909
267.9 280.7 4.56% 260.8 2.65% 10 31.635
262.1 285.7 8.26% 258.2 1.49% 15 31.182
255.5 288.0 11.28% 254.5 0.39% 20 30.553
247.3 286.9 13.80% 248.9 0.64% 25 29.751
237.4 282.0 15.82% 241.3 1.62% 30 28.785
226.0 273.3 17.31% 231.6 2.42% 35 27.660
213.4 261.1 18.27% 220.0 3.00% 40 26.385
200.0 245.9 18.67% 206.8 3.29% 45 24.971
185.0 228.0 18.86% 192.1 3.70% 50 23.427
169.2 208.0 18.65% 176.3 4.03% 55 21.766
153.1 186.6 17.95% 159.7 4.13% 60 20.000
136.7 164.2 16.75% 142.4 4.00% 65 18.143
120.2 141.4 14.99% 124.9 3.76% 70 16.208
104.0 118.8 12.46% 107.4 3.17% 75 14.212
88.0 96.9 9.18% 90.0 2.22% 80 12.168
72.8 76.4 4.71% 73.4 0.82% 85 10.092
58.6 59.1 0.85% 59.1 0.85% 90 8.000
This is a prime example of the error with the original equation. At
only 10 or 15 degrees, the error is already up to 10% and climbs. I
chose to use the angle itself for the factors reference point. It
simply sharpens the inductance closer to reality and gets the error
down to a usable and acceptable level. Note, this equation is fine
for all 3 geometry styles.
Sorry for not including the factor when I first posted (I bet you
were scratching your head on that one ;-) ). Of course, with the new
programs, "out with the old and in with the new". But, for a basic
differential, it's good.
I am trying to hit the basic, often used, equations that one really
"needs". It won't have toroid-plat-sphere capacitance or Medhurst
stuff since that really needs the computer programs now that we
have good programs to figure it out right... I have not used those
since the E-Tesla days...
Agreed! It's one thing to calc an objects C, but quite another to
distribute it correctly.
I will put in surge impedance. "I" have never used it for much but
others like it ;-))
Often it's been used in postings by various members and that was the
only reason I threw it out there. So people could throw a number to
it if wanted. I personally have only looked here and there to get a
feel for it, nothing more.
The new document looks great! Good work.
Take care,
Bart