Re: TC Inductance Formulas...

On this from Tim Chandler....

> I was going through some old TC notes and discovered I had atleast 4
> different formulas to calculate the inductance of a coil (air-core).  The
> problem is all these formulas give different answers (some +/- 5 mH).  My
> question is, which one is right(if any)?  Rather than post all the formulas
> I thought I would ask if any knew of a formula for inductance that is
> EXTREMELY close to the true measured inductance of the coil?  

> Any help appreciated...

I've been using Wheeler's with a slight modification for helical 
coils. Instead of a bottom line = 9r + 10h,  I've been using a
bottom line = 10(r + h). It seems slightly better for typical
Tesla secondaries. In any case, Wheeler seems to come within about
5% worst case and often better in my experience.