Re: Sphere/Toroid Comparison Chart

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Terry, 

Yep, I've been trying to keep up with TSSP. The change in inductance is noted
in the back of my mind. This of course reduces Ctop variance, but in the realm
of design programs such as JavaTC, JHCTES, Ed Sonderman's spreadsheet, etc...
it makes no difference if L or C is modified to account for the change in Fr.
Fr is what is most important in these programs because Fr and coupling are the
links between primary and secondary, all of which equate to the correct tap
position and primary to secondary proximity. The main problem is and has been
the affect of Ctop on Fr. 

I and many I assume, knew Bert's Pool's Ctop equation was for the terminal in
free space and not in proximity to coils, walls, ground, etc. I think this
equation will live on in TC design but needs added equations to account for the
terminal to ground, to walls or objects, and to the secondary turns if used in
the above programs. 

Then again, we could easily apply Fr change strictly to inductance and leave
Ctop alone. I wonder if top capacitance really is affected? Maybe it is better
to think in terms of inductance. Even though the top terminal is directly
connected to the top of the secondary, the top terminal's size and proximity
will couple with the secondary. 

Hmmm, I wonder what a flat primary (2) at the bottom and top of the secondary
would reveal? (directly connected at the top). 

Wheeler W 
        h 
        e 
        e 
        l 
        e 
Wheeler r 

Just thinking here, 
Bart A. 

Tesla list wrote: 
>
> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net> 
>
> Hi Bart, 
>
> There is another fun twist to all this.  When a top load is added to a 
> secondary coil, the voltage profile along the coil changes which affects 
> the coils effective inductance.  The inductance can actually drop as much 
> as 20% do to this effect.  See: 
>
>
> <http://hot-streamer-dot-com/TeslaCoils/MyPapers/NSVPI/NVSPI.htm>http://hot-st
> reamer-dot-com/TeslaCoils/MyPapers/NSVPI/NVSPI.htm 
>
> for my actual voltage profile measurements and: 
>
>
> <http://www.abelian.demon.co.uk/tssp/pn1710/>http://www.abelian.demon.co.u
> k/tssp/pn1710/ 
>
> for Paul's computer analysis of this. 
>
> BTW - Paul's computer analysis was generated long before the actual 
> measurements were taken which confirmed the models.  Another triumph of 
> computer modeling :-))) 
>
> E-Tesla6 uses voltage profile curve fitting from Paul's TSSP data to 
> account for this effect.  Those interested should check out the mass of 
> fascinating information at: 
>
> <http://www.abelian.demon.co.uk/tssp/>http://www.abelian.demon.co.uk/tssp/ 
>
> We will be studying the remarkable implications of this work for decades to 
> come!! 
>
> Cheers, 
>
>         Terry 
>
> >At 08:48 PM 5/8/2001 -0700, you wrote: 
> >John, Terry, All, 
> > 
> >I've tested my two toroids and my measurements "do not" agree with less than
>
> >20% reduction of Ctop. 
> >See below: 
> > 
> >Tesla list wrote: 
> >Original poster: "John H. Couture by way of Terry Fritz 
> ><twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net> 
> > 
> >Terry - 
> > 
> >I entered your coil's data into the JHCTES Ver 3.2 program to see what it 
> >comes up with for a toroid. To get the 87.66 Khz the program came up with 29
>
> >pf for the capacitance. This is about 12% less than the graph shows (space 
> >33 pf) for an 8 x 30 toroid. On my web site I mention that the graph 
> >capacitance would be reduced about 20% when placed on the TC secondary. It 
> >appears this may be too high a percentage. We will have to wait until more 
> >data is obtained. 
> >I've been doing some toroid Fr tests the last couple weeks. 
> > 
> >Purpose: To measure the change in Fr vs. calc'd with two different toroid 
> >dimensions and also to check Ctop against Bert Pool's equations when C 
> >is placed on the secondary. 
> > 
> >Method: Frequency meter (0.1% accuracy at these frequency's) using Terry's 
> >TC Tuner. The secondary is set upon a pvc pipe stand (no primary). Toroids 
> >are lowered via pulley arrangement to measured distances. Tuner connects 
> >between bottom sec. winding and RF ground. Tuner dial is "finely" turned to 
> >acquire Fr indicated by led brightness. Tuner is measured with Frequency 
> >meter. 
> > 
> >This may sound a bit odd, but the tuner measurement is within 1kHz of 
> >measurements taken via oscope and loop antenna (running) and I checked it 
> >against E-Tesla6 (of who's Fr accuracy was less than 1kHz), so the method 
> >"is" working. The tuner acts as a device that captures the Fr. Every coiler 
> >should build one of these (it's so simple). Great job Terry! 
> > 
> >Toroids are precise measurements via circumference measurements: 
> >Toroid No. 1 = 7.7" x 32" at a calc of 35.2pF. 
> >Toroid No. 2 = 6.5" x  37.9" at a calc of 39.2pF. 
> >Secondary: 12.75" x 43.25". 
> > 
> >Toroid No. 1 (7.7" x 32") 
> >Level    CalcFr    MeasFr    CalcC     MeasC 
> >(inch)    (kHz)     (kHz)     (pF)      (pF) 
> > 
> >-1        76.8     88.8      35.2       21.0 
> > 0        76.8     88.4      35.2       21.4 
> > 2        76.8     87.8      35.2       22.5 
> > 3        76.8     87.6      35.2       22.1 
> > 4        76.8     87.0      35.2       22.7 
> > 6        76.8     86.8      35.2       22.9 
> > 8        76.8     85.9      35.2       23.9 
> > 10       76.8     84.7      35.2       25.2 
> > 
> >Toroid No. 2 (6.5" x 37.9") 
> >Level    CalcFr    MeasFr    CalcC     MeasC 
> >(inch)    (kHz)     (kHz)     (pF)      (pF) 
> > 
> >-1        74.2     82.8      39.2       27.3 
> > 0        74.2     82.6      39.2       27.6 
> > 2        74.2     82.2      39.2       28.0 
> > 3        74.2     81.8      39.2       28.6 
> > 4        74.2     81.3      39.2       29.2 
> > 6        74.2     81.1      39.2       29.4 
> > 8        74.2     80.6      39.2       30.0 
> > 10       74.2     79.7      39.2       31.2 
> > 
> >With Toroid No.1 data, the Fr ranges from 15.6% to 10.3% (closer to 
> >calculated Fr as toroid height is raised). Ctop for the toriod ranges from 
> >40.3% to 28.3%! That's a affect (possibly due to large coil?). 
> > 
> >With Toroid No.2 data, the Fr ranges from 11.6% to 7.4%. Ctop for the 
> >toroid ranged from 30.4% to 20.4%. 
> > 
> >Other than the obvious (reacts as one would expect) height changes, 
> >something here does standout: 
> > 
> >Toroid No.1 is larger in cord diam. and smaller in outer diam. Thus, Toroid 
> >No.2 is "physically" farther away from the secondary and therefore less 
> >affected. Both toroids calc'd capacitances are similar, but toriod 
> >"proximity in relation to the secondary" appears to play a major roll in 
> >both Fr and Ctop change. 
> > 
> >I don't see a standard percent value we can throw to this (although anything
>
> >is better than nothing). I know my secondary is on the large side and might 
> >be why my values for Ctop vary far more than 20%. 
> > 
> >If you have a huge cord size that is "suppose" to have a large Ctop value, 
> >you may be better off with a smaller cord size at a wider diameter (not 
> >because of the Ctop value, but due to the toroids proximity to the 
> >secondary). 
> > 
> >BTW, I also mounted the toriods on top of each other at 3" and 14" 
> >distances. By using 50% of each and applying these values to Bert Pools 
> >standard toroid equation (as d1 and d2), the accuracy was amazing (3% to 
> >0.6% from measured). I also swapped toroids (who was on top) and there was 
> >very little change (I didn't expect that). 
> > 
> >BTW, the above data's toroid height was measured from top secondary winding 
> >to bottom plane of toroid. This of course was adjusted for center of toroid 
> >when using E-Tesla 6. BTW, at a hieght of 0 on the 7.7 x 32 toroid (or 3.85"
>
> >for E-Tesla 6), I measured 88.4kHz and E-Tesla 6 predicted 88.49kHz. Pretty 
> >good program and Tuner! 
> > 
> >For E-Tesla 6, wall distance is used, but often times there are objects 
> >around that can affect Fr including my own body. One wall was at 80" and the
>
> >other 3 were more than double that. I used the nearest wall at 80". Amazing 
> >program! BTW, ceiling height is 120", and I did "not" include a primary in 
> >the program (0 for all primary inputs - worked perfectly and was how I 
> >measured the coil). The primary should change results and then possibly Ctop
>
> >would be in the 20% range or less. Maybe that is the next test. 
> > 
> >There is a proximity relationship here between toroid and secondary. I can't
>
> >conclude much until a smaller coil is tested with these same toroids and 
> >test parameters (time to wind a 6" diameter coil). 
> > 
> >Just thoguht I'd share my results. Any thoughts from the list? 
> > 
> >Take care, 
> >Bart A. 
> >