Re: Sphere/Toroid Comparison Chart

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Terry,

On 8 May 01, at 23:23, 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
> 
> for my actual voltage profile measurements and:
> 
> http://www.abelian.demon.co.uk/tssp/pn1710/
> 
> for Paul's computer analysis of this.

That is not at all unreasonable considering the coupling which must 
exist between what is essentially a bunch of parallel shorted turns 
and the top of the windings. I might suggest a further twist to be 
analysed in the tssp project: what effect does cutting a slit in the 
terminal have on the L/C distribution in the resonator? I've done 
this and the frequency changes very little despite the removal of the 
shorted turn (goes up a little from memory) so ???????????

Regards,
malcolm

> 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/
> 
> 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.
> >
> 
> 
>