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Re: Toroid Capacitance Equations



Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com> 



John:

Can you pass along the "D" factor for the following additional sizes:

24 inch x 6
30 inch x 7
34.5 inch x 8.5
48 x 12 inch


Do you usually subtract 10% as a "shielding" factor when the toroid is atop
a coil?  Typical would be coilform size = 1/2 toroid major dia.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913
 >
 > To All -
 >
 > Over the past years I have collected about a dozen various equations for
the
 > capacitance of a toroid. The accuracy of these equations vary greatly and
 > none of them are very accurate for a particular toroid. I have found that
 > having only a single equation for all sizes of toroids that give accurate
 > results requires a very complicated equation. In order to simplify the
work
 > of calculating the toroid capacitance I have found that 4 simple equations
 > can give acceptable results.
 >
 > The 4 equations are for toroids with minor diameters of 3", 6", 12", and
 > 20". The equations do not give the exact capacitances that Antonio's INCA
 > program (meters) shows but they will be very close. In fact the equations
 > will give good accuracies for minor diameters that are between the
3,6,12,20
 > inch if you extrapolate between the capacitances obtained for these minor
 > diameters.
 >
 > d = Minor diameter in inches
 > D = Major overall diameter in inches
 > Note that D must be at least twice d.
 >
 >     d = 3"    pf = 1.6079*(D^0.8419)
 >     d = 6"    pf = 2.0233*(D^0.8085)
 >     d = 12"   pf = 2.0586*(D^0.8365)
 >     d = 20"   pf = 2.2628*(D^0.8339)
 >
 > The Toroid Capacitance Graph in my TC Notebook shows four capacitance
curves
 > that were made before INCA's exact capacitances became available. The
 > Notebook curves were made from equations that are similar to the
up-to-date
 > ones shown above.
 >
 > If you have any questions please let me know.
 >
 > John Couture
 >
 > ------------------------------------
 >
 >
 >