cc: tesla-at-grendel.objinc-dot-com Richard, I was looking at some formulas you published on 8-10-95 (Tesla Math Formulary). Re: Equation # 6, Frequency of Coil, does this formula take into account the self capacitance of the coil? What is the equation for self capacitance? I assume the above formula is for close wound coils, is this corrrect? How do you do calculations for space wound coils? Thanks, Ed Sonderman