[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*To*: tesla-at-pupman-dot-com*Subject*: Re: New formula for secondary resonant frequency*From*: "Tesla list" <tesla-at-pupman-dot-com>*Date*: Sat, 03 Feb 2001 13:26:48 -0700*Resent-Date*: Sat, 3 Feb 2001 13:42:37 -0700*Resent-From*: tesla-at-pupman-dot-com*Resent-Message-ID*: <Wg6gdD.A.w5D.20Gf6-at-poodle>*Resent-Sender*: tesla-request-at-pupman-dot-com

Original poster: "harvey norris by way of Terry Fritz <twftesla-at-uswest-dot-net>" <harvich-at-yahoo-dot-com> --- Tesla list <tesla-at-pupman-dot-com> wrote: > Original poster: "by way of Terry Fritz > <twftesla-at-uswest-dot-net>" <paul-at-abelian.demon.co.uk> > > Hi All, > > Calculator fiends may like to try out the following > formula for > estimation of secondary resonant frequency. Applies > to bare coils > (ie no top-load and no primary) in normal > grounded-base configuration, > when situated over a reasonably well defined ground, > with the coil > base not more than half the coil length above > ground. > > Starting with: > > turns; > h = length of secondary winding, metres; > d = diameter of secondary - metres; > b = height of winding start above ground - metres; > awg = wire gauge, AWG; > > (metres = inches * 0.0254) I do not understand this here, or the formulas. You start with 4 variables: h,d,b,awg and then somehow conclude that only 2 are necessary by the finished assumption fb = log( b/h/0.2) I dont know what f(b) is supposed to indicate but taking the ln or log(e)symbol as then natural log as you indicate, there still seems the problem of whether you are indicating whether the quantity equals ln([b/h]/0.2) or ln(b/[h/0.2]) which I think can be different quantities. Also the finished equation demanding another variable s Fres = s * (1.02 + fb/98.9065); Can you be more specific as to what the quantity s is? The wire diameter divided by the height of the coil is already a small number but when we in turn multiply that by the turns we are only reaching the value of h again? I am truly confused here, are the rest of the numbers some kind of computer coil program? Confused In Ohio HDN > Compute: > > x = h/d (form > factor) > wd = 7.348e-3/pow(1.122932, awg-1) (wire > diameter - metres) > sr = turns * wd/h (spacing > ratio) > > fa = -94.6683*awg*awg*awg + 9000.55*awg*awg - > 301175*awg + 3.64056e+6 > fs = 3.50662*sr*sr - 7.90171*sr + 5.83019 > fx = -0.000211179*x*x*x + 0.00557568*x*x + > 0.0664809*x - 0.0153254 > t = fa * fs * fx/h/h > s = -3.85188e-15*t*t*t + 1.17176e-8*t*t + > 0.631829*t + 482.463 > > and finally, > > fb = log( b/h/0.2) (use the > natural logarithm) > Fres = s * (1.02 + fb/98.9065); (Hertz) > > Accuracy is around 2% average, with a peak error of > around 4%. > > Some examples: > > My big CW coil: b=0.15, h=1.6, turns=725, awg=12, > d=0.58; > Measured 90.9 kHz, formula 90.2 kHz, > -0.8% error > > My half-coil: b=0.15, h=0.8, turns=365, awg=12, > d=0.58; > Measured 150.7 kHz, formula 151.4 > kHz, +0.5% error > > Terry's big coil: b=0.025, h=0.762, awg=24, > d=0.2606, turns=1001; > Measured 148.4 kHz, formula 146.1 > kHz, -1.5% error > > Marc Metlicka's > large h/d coil: b=0.3302, h=1.07696, awg=24, > d=0.1081, turns=1700; > Measured 276.9 kHz, formula 276.9 > kHz, 0.0% error > > The formula was derived by curve fitting to a > database of around > 1700 simulated secondary coils, and is expected to > be more accurate > than estimates based on Medhurst capacitance. > > Regards, > -- > Paul Nicholson, > Manchester, UK. > -- > > > ===== Binary Resonant System http://members3.boardhost-dot-com/teslafy/ __________________________________________________ Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo-dot-com/

- Prev by Date:
**Re: 3 Phase - again** - Next by Date:
**Re: Spark Dissipation** - Prev by thread:
**Re: New formula for secondary resonant frequency** - Next by thread:
**RE: New formula for secondary resonant frequency** - Index(es):