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Re: JavaTC and ETesla6 Questions
Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
Hi Adam, Terry, All,
I must apologize for not being able to discuss this earlier with you.
There's been a serious illness
in my family and I had to drive out of state this weekend. I just returned
last night about 2am.
This is the first chance I've had to take a look at this.
Yes, JavaTC will give a high Cself because it is using Medhurst K. If we
use Paul's equations for
Ces, we will see 23.53pF. This is a fantastic example where Medhurst
introduces error when outside
it's hd range and obviously increases the further hd increases. Adam, as
far as hd being used in
these equations, they all use it, including the value 23.53pF shown above.
Let me point you to
Paul's TSSP information which will clarify the equations I used to find
23.53pF. This is the main
page. There are a couple links specific to these equations and Medhurst.
The first is "Various
Formulae" and the second is "Miscellanae".
http://www.abelian.demon.co.uk/tssp/
Adam, you did exactly as you should have with JavaTC. You were right to run
E-Tesla6 and yes,
because of Cself value being high, the Top Load Reduction was 97.6%. In the
end, using this % would
have produced the correct resonant frequency and correct total resonator
capacitance of 33.38pF as
E-Tesla6 identified. Obviously, it has to and is why I promote E-Tesla6
every chance I get. It has
never let me down and I've probably used it more than anyone (nearly on a
daily basis for one coil
or another).
There was a discussion on the list a few months ago regarding the use of
Medhurst. The discussion
ended with CMed being close enough in most coil designs. Since that
discussion, I've been
contemplating pulling in Paul's equations. Your coil is the first coil that
has shown a major
disagreement with CMed. Of course, it isn't verified until you actually
build and measure it, but I
will put my money on Paul's equations for equivalent series inductance and
capacitance to come out
very near your measurements.
JavaTC is fluid, always looking for ways to improve it's accuracy and use.
I will pull in Paul's
equations. I've already performed the leg work for incorporating them into
JavaTC and have been
waiting for this type of situation to occur. Using JavaTC with the 97.6%
top load reduction is fine,
just note that the individual values (top load and secondary capacitance)
will not be correctly
defined. The lumped value is correct. Also, I will be changing the term
"top load reduction" to
something reflecting the total capacitance because it IS the total
resonator capacitance that is
affected by top load, secondary, ground plane, surrounding objects, walls, etc.
Adam, THANK YOU for taking the time to ask the question and for providing
full information. The only
way those of us who provide design calculators can keep our programs up to
par is to get "feedback"
from list members. That's true for JHCTES, WinTesla, JavaTC, and any of the
other calculators out
there. It's the same for projects that strive to define the physics
involved with coils (such as the
TSSP). We can model coils all day long, but verification comes from
feedback of controlled and well
defined measurements on "real" coils.
For your design, you asked which is correct, a Cself of 32.74 or 23.6?
I would say 23.6pF is correct for the self capacitance.
The toroid by itself (alone in the world) is 26.5pF.
The total resonator capacitance with toroid in position is 33.36pF.
So, 23.6 + 26.5 = 47.1pF. Now, because of the toroid, walls, etc., the
total resonator capacitance
is reduced to 33.36pF. Note, the toroid placement on the coil has reduced
the total capacitance to
29.17% of it's original lumped value. This total resonator capacitance will
change as you reposition
the toroid, move the coil nearer/further to walls, place objects near the
coil, etc.
Hope this helps clarify some of the confusion here.
Take care,
Bart
Tesla list wrote:
> Original poster: "Yurtle Turtle by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <yurtle_t-at-yahoo-dot-com>
>
> You're right. I missed that. JavaTC gives me Cself of
> 32.74. I've seen two formulas for calculating Cself.
> One gives me 23.6, while the other gives 31.22. The
> second formula is pretty horrendous, and uses an H/D
> factor. Apparently JavaTC uses something similar to
> the latter formula.
>
> In my last coil, this made little difference, since I
> had a fairly low H/D. This proposed coil has a much
> higher H/D.
>
> Which formula is more accurate?
>
> Adam
>
> --- Tesla list <tesla-at-pupman-dot-com> wrote:
> > Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> >
> > Hi Adam,
> >
> > The toroid capacitance for Java TC is too high. I
> > "think" you want 33.36pF
> > - The seconday coil's self capacitance of about 24pF
> > for toroid
> > capacitance. That is about 9.44pF.
> >
> > 33.36 - 23.92 = 9.44pF
> >
> > Cheers,
> >
> > Terry
> >
> >
> > At 11:06 AM 9/1/2002 -0700, you wrote:
> > >Please excuse the long post.
> > >
> > >I'm getting ready to build another coil, and was
> > >attempting to use JavaTC and ETesla6, when I ran
> > into
> > >something that didn't seem right. To begin with, I
> > >plugged the following into JavaTC:
> > >
> > >Secondary Diameter 8.125
> > >Secondary Height 69
> > >Bare Wire Diameter .0403
> > >Insulation Thickness .0014
> > >Spacing Between Turns 0
> > >Toroid Major Diameter 24
> > >Toroid Minor Diameter 6
> > >Sphere Diameter 0
> > >Top Terminal Reduction 0
> > >
> > >Which gave me:
> > >
> > >Number of Turns 1600.9
> > >Inductance 58.22
> > >Toroid Capacitance 26.5
> > >Loaded Resonant Frequency 85.69
> > >
> > >OK so far.
> > >
> > >Then I used the following in ETesla6:
> > >
> > >*Grid Size
> > >150
> > >*Units of Measure
> > >*1 = mm
> > >*2 = cm
> > >*3 = inches
> > >*4 = Feet
> > >*5 = meters
> > >3
> > >*1-Bare 2-Terminal
> > >2
> > >*Ceiling Height
> > >188
> > >*Wall Distance
> > >120
> > >*Primary Inner Turn Height
> > >24
> > >*Primary Inner Diameter
> > >11.125
> > >*Primary Outer Diameter
> > >22.375
> > >*Primary Outer Turn Height
> > >24
> > >*Strike Rail Height
> > >0
> > >*Strike Rail Diameter
> > >0
> > >*Secondary Base Height
> > >25
> > >*Secondary Diameter
> > >8.125
> > >*Secondary Winding Length
> > >69
> > >*Meaured Secondary Inductance
> > >58.22
> > >*First Top Terminal Center Height
> > >94
> > >*First Top Terminal Cord Diameter
> > >6
> > >*First Top Terminal Center to Center Diameter
> > >18
> > >*Second Top Terminal Center Height
> > >0
> > >*Second Top Terminal Cord Diameter
> > >0
> > >*Second Top Terminal Center to Center Diameter
> > >0
> > >*Top Terminal Voltage
> > >100
> > >*Begin Run Approval
> > >1
> > >
> > >Which gave me:
> > >
> > >Ccalc 33.36432
> > >Fcalc 114193.89
> > >
> > >Here's where it get's wierd. In order to "force"
> > >JavaTC to match these results, I had to enter 97.6%
> > >for Top Terminal Reduction. Is that possible?
> > Surely I
> > >made a mistake somewhere.
> > >
> > >thanks
> > >Adam
> > >
> > >=====
> > >Adam Minchey
> > >yurtle_t-at-yahoo-dot-com
> > >http://www.geocities-dot-com/yurtle_t/index.htm
> > >
> >
> >
>
> =====
> Adam Minchey
> yurtle_t-at-yahoo-dot-com
> http://www.geocities-dot-com/yurtle_t/index.htm
>
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