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Re: Optimal toroid elevation
Hi Terry, (All),
I will remeasure inductance values and try E-Tesla5.2 again. Yes, I did
download it last night and used it today at work to plot test#2 and yes, it is
quite a bit faster now. It worked flawlessly as well. Last night I looked at
E-Tesla5's output and compared to measurement and did the same with todays
plots. I used Level 3 and looked at pass 3000 for both:
TEST#1 (toroid at top plane of secondary)
E-Tesla5:
Cself = 43.6pF, Fcalc = 81.4kHz (Toroid then = 22pF)
Measured:
Cself = 38.8pF, Fmeas = 86.2kHz (Toroid then = 17.2pF)
Cself error = 11%, Ctop error = 21.8%
TEST#2 (toroid raised 22" from position of Test#1)
E-Tesla5:
Cself = 54.3pF, Fcalc = 72.9kHz (Toroid then = 32.7pF)
Measured:
Cself = 49.8pF, Fmeas = 75.7kHz (Toroid then = 28.2pF)
Cself error = 8.3%, Ctop error = 13.7%
E-Tesla5 is modeling the coil very well as far as what occurs when the toroid
is raised (the capacitance increases and the error margin reduces), but with
regards to the toroid capacitance, I'm not sure if the toroid is increasing or
if the complete resonators capacitance is what is increasing. I suspect Ctop is
seeing the added capacitance and possibly Cs is seeing a slight increase based
on the above method.
Terry, the inductance may very well be playing a part as far as not getting the
numbers right on the money, but it's expected as there are so many margins for
error. Another possibly in the error margin is ceiling and wall distances. My
coil is not center to the garage, it is closer to the garage door and in front
of the coil there is 18 ft, 11 ft on each side, 4 ft behind (this is how the
test was run and run at low power levels). I averaged the area around the coil,
however, I think with field distribution, this pulls error into numbers (not as
bad as I expected - E-Tesla5.2 is an excellent program! - it really surprised
me.)
My test was to see if E-Tesla5 would model the increase in C, and it did very
well. I measured 11pF increase in Ctop, and E-Telsa plotted 10.7pF! I think
this is significant considering the toroids stand alone capacitance is 36.9pF
(about 1/3).
The two graphs are very different. I would have loved to post them, but my home
pc is getting a disk error trying to read the diskette I put the outputs of
E-Tesla5 on (figures, eh?). Well, that will need to wait until next week when
I'm back at work (going camping this weekend).
Take care,
Bart
Tesla List wrote:
>
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
> Hi Bart, Jeff, Marco,
>
> There is a subtle detail here you need to be aware of.
>
> As long as the torroid is raised a few inches above the top of the
> secondary, the program should work fine. However, if you are setting the
> toroid directly on top of the secondary, it is probably changing the
> secondary coil's inductance. Try to remeasure the secondary's inductance
> with the toroid in place as in Test #1 below. It will probably be about
> 10% lower than without the torroid in place. I did a quick test and my big
> coil went from 75.4mH to 68.9mH (about an 8.6% drop in inductance) The
> torroid is messing with the secondary's inductance since it is so close.
> In a normal coil, the little distance between the top of the secondary and
> the toroid provides enough isolation. However with them in almost direct
> contact, the secondary inductance will change. Since E-tesla does not
> account for this inductance variation, it will not give the best answer.
> This may also be a problem if you have a corona ring on the top of the
> secondary but I "think" that ring should have a split in it which should
> fix the problem??
>
> I think if you use the new measured value of inductance, E-Tesla will
> give
> the right answer. However, the very close large metal toroid may alter the
> voltage distribution a bit?.? I really don't know for sure.
>
> BTW Marco, E-Tesla does "try" to find the "true" volts-per-unit-distance
> in the stress output file (Soutput.xls). However, I think it is not doing
> it correctly. I will look at it more and get it fixed. It can easily do
> it, but I just have to be sure it is correctly programmed (this time
> ;-))... Stay tuned!
>
> BTW Bart, Be sure to get the latest version of E-Tesla5.2x ("yesterday's"
> version ;-)). It now runs 2.5 times faster thanks to Finn's brother
> finding the problem with using floating point variables where they were not
> needed!!
>
>
> <http://users.better-dot-org/tfritz/site/programs/E-TESLA5.ZIP>http://users.be
> tter-dot-org/tfritz/site/programs/E-TESLA5.ZIP
>
> By far the greatest advantage of having this program in simple BASIC is
> that so many people can easily look it over and make all kinds of great
> suggestions!! This has really help the program tremendously!!
>
> Cheers,
>
> Terry
>
> >At 07:10 PM 5/25/00 -0500, you wrote:
> >Jeff & Marco,
> >
> >I just measured this, and it is definately large enough to be significant.
> >However, as Marco pointed out, if the toroids out of reach, then it's out of
>
> >reach (definately stick with the primary).
> >
> >Here were the results of my test. The winding dimensions are 12.5" x 44.5",
> >18awg,
> >CS=21.6pF, Ls=87.6mH.
> >
> >Ctop = 34" x 7.4" and calcs to 36.9pF (70.3kHz)
> >
> >Test #1:
> >Toroid at top plane of secondary. Measured 86.2kHz.
> >Ctop then calcs to 17.2pF (53% error from original calc).
> >
> >
> >Test #2:
> >Toroid raised 22" up. Measured 75.7kHz.
> >Ctop then calcs to 28.2pF (23.5% error from original calc).
> >
> >This test also held true for a 16" sphere. Of course, capacity's were
> >different but the results were the same (11pF gain in Ctop is significant).
> >Jeff, did you model this with E-Tesla5? I took E-Tesla5 to work today to run
>
> >on a faster pc and ran the setup mentioned above (true measured values were
> >input into the program). The program showed 76kHz for Test #1 (but this is
> >not what I measured). I need to rerun E-Tesla5 for Test #2 as I put in the
> >wrong toroid height. I have a feeling it is going to be near 73kHz. I'll
> >post this result tomorrow.
> >
> >Take care,
> >Bart
> >
> >Tesla List wrote:
> >Original Poster: "Jeff W. Parisse" <jparisse-at-teslacoil-dot-com>
> >
> >Barton & Marco,
> >
> >> Marco, you may want to consider making the toroid movable up and down.
> >Malcolm
> >> posted in a reply this week about fine tuning the resonator simply by
> >raising
> >> or lowering the toroid. Makes a lot of sense to me.
> >
> >I modeled this with E-Tesla 5.1 and tested with real parts. The amount of
> >Fsec
> >shift due to different toroid heights is too small to be significant on a
> >big coil
> >(like the Model 9J).
> >
> >Jeff
> >