Tesla List wrote: > ... I could of > course use Medhurst's formula (is there a table for H/D ratio > 5?), but > I wanted to know if there's another way to calc it too. > BTW: It's only going to handle metric units! Here is a more direct formula, by Medhurst too, and in metric units: L=coil length in meters, R=coil radius in meters. capacitance=(11.26*L+16*R+76.4*sqrt(R*R*R/L))*1e-12 Farads Antonio Carlos M. de Queiroz