Inductor Coil Parasitic Capacitance

2017/2/4 19:49:59

I have a formula for predicting the capacitance of an air core inductor.

Cparallel (pF per turn) = B * Er / {11.45*cosh^-1(S/D)}

where B = coil diameter mm

Er = dielectric constant (of air) = 1

S = gap between the coil turns mm

D wire diameter mm

I think cosh^-1 is the inverse cosh function.

Can I get a scientific calculator to give that answer, when S/D = 1?

If I press

2ndF, then hyp, then cos (1), I get 0

hyp, then 2dF then cos (1), I get 0

hyp, then cos (1), I get 1.54

Any idea if any of these answers could be correct?

Antonio Rubio Llorca

2017/2/6 19:49:59

Thanks for marvelous posting.