Re: Windings vs. Diameter - errors

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Ed Phillips <evp@xxxxxxxxxxx>

   One easy way to get a pretty good check on the total wire length 
is to measure the DC resistance and divide by the "table values" for 
resistance of that wire size.  Knowing the wire length, diameter, and 
the OD of the form you can calculate the number of turns easily, 
remembering that the effective turn diameter is the OD plus the wire 
diameter.  I've found it checks within a percent or so at the worst.
Of  course, just counting the turns as you wind is still the easiest 
and best way.

Ed

   As for "Medhurst inductance", remember that there is more than 
one approximate formula, depending on the L/D ratio, and that there 
are simple and more accurate formulae readily available.  Considering 
the effective operating bandwidth of our coils, is great accuracy of 
any interest other than as a subject unto itself?