RE: JavaTC and ETesla6 Questions

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi John,

I think all three of us are getting 23 or 24pF for the coil's self
capacitance.  No problem there.

But the toroid's height above the coil and it's general location inside the
secondary's E-fields can have a dramatic effect on Fo independent of the
toroid's dimensions or the toroid's stand alone capacitance in free space.
I think your program estimates those effects to some degree.

However, E-Tesla6 was designed to specifically calculate Fo give all the
needed dimensions of coil, secondary, toroid, and room. It can easily
calculate the Fo for a coil and toroid and find the change in Fo given a
change in toroid height.  Given accurate input dimensions, it can find Fo
to within 2% easily.

Given Adam's dimensions and E-Tesla6 input data, I calculated his coil in a
400 point grid (his 150 grid size was just a little light) and rechecked
the coil's placement in the detect circle and room (the program should warn
if those are too far off).

So, E-Tesla 6 in a 400 point grid (prolly not worth the 48 trillion
calculations for the tiny bit of extra accuracy ;-)) gives an answer of...  

 E-TESLA  V6.11C  November 21, 2000 
  
 Grid Size = 400.000000
 Scale Multiplier = 1.000000
 Terminated Coil
 Ceiling Distance = 188.000000
 Wall Distance = 120.000000
 Primary Height (Inner Turn) = 24.000000
 Primary Inner Diameter = 11.125000
 Primary Outer Diameter = 22.375000
 Primary Height (Outer Turn) = 24.000000
 Strike Rail Height = 0.000000
 Strike Rail Diameter = 0.000000
 Secondary Base Height = 25.000000
 Secondary Diameter = 8.125000
 Secondary Length = 69.000000
 Secondary Inductance (mH) = 58.220003
 Terminal-1 Height (center) = 94.000000
 Terminal-1 Cord Diameter = 6.000000
 Terminal-1 C-C Diameter (toroid only)= 18.000000
 Terminal-2 Height (center) = 94.000000
 Terminal-2 Cord Diameter = 0.000000
 Terminal-2 C-C Diameter (toroid only)= 0.000000
 Top Voltage = 100.000000
 Pass     Ccalc (pF)          Change            Fcalc (Hz)
  1000   C=1.33970       Err%=133869.750000       F=569876.38
  2000   C=4.35564       Err%=225.121521       F=316051.44
 ...
115000   C=32.79461       Err%=0.000127       F=115181.51
116000   C=32.79465       Err%=0.000127       F=115181.44
117000   C=32.79464       Err%=-0.000042       F=115181.46


115.81kHz is "my" guess ;-))

Paul's TSSP programs are more accurate still.  I think they calculate
Gaussian surfaces the same as E-Tesla but the voltage profiling on the
secondary is more refined (However, E-tesla now uses curve fitted equations
from Paul's work).  As I write this, I wonder if Paul's program take into
account strike rails, the primary, the rod from the top of the secondary,
and the toroid's center plate section?  It may be general enough to do
these, and much more?

So, somebody is ~15% off here :o))  We'll just have to wait till Adam's
coil is built to find out for 'sure' ;-))

BTW - I am surprise Bart uses E-Tesla so much (nearly on a daily basis)!
:-)))  Paul's equations seem rock solid to me so I think using them in
JavaTC (or any program) could only make it better.

Cheers,

	Terry


At 12:07 PM 9/2/2002 -0700, you wrote:
>
>Terry, Adam -
>
>The operating frequency for the secondary coil with toroid should be about
>97 not 114 Khz. For example enter into the JHCTES Ver 3.3 on-line program
>for the secondary inputs only (The power transformer and primary inputs are
>not necessary):
>
>Sec Rad = 4.06      Sec Turns = 1600.9
>Turns/inch = 1600.9/69 = 23.20
>Sec above primary = 0.00
>Sec Term pf = 22.4 (estimate)
>
>Press calculate for Outputs -
>Coil self cap     = 23.29 pf (Medhurst equation - long form)
>Total sec cir cap = 23.29 + 22.40 = 45.69 pf
>Oper Freq         = 97.65 Khz
>
>The 6 x (18+6) toroid = about 28 pf (from Grapf)
>When placed on the secondary coil the pf reduction is estimated to be about
>20% or 5.6 pf. The program sec term = 28 - 5.6 = 22.40 pf
>
>The only way to find the true reduction of toroid capacity when placed on
>the sec coil is to properly test for the actual capacity after the coil and
>toroid are built. This simple test is shown in the Tesla Coil Construction
>Guide and other books.
>
>The test consists of finding the actual frequency of the sec coil with the
>toroid in place. Going back to the JHCTES program the sec term pf input of
>the program is then adjusted until the test frequency appears in the program
>outputs. This new sec term pf will be the true toroid capacitance of your TC
>system and will be close to the 22.40 pf design capacitance.
>
>The amount of reduction (about 5.6 pf or 5.6/28 = .20) can then be easily
>determined. Note that the 20% reduction is only an estimate and will vary
>depending on the construction of the sec coil and toroid.
>
>You can arrive at a similar conclusion with JavaTC and ETesla but this
>requires more work on your part.
>
>John Couture
>
>----------------------------
>