# Re: Frequency calculations

```Tesla List wrote:
>
> >From Esondrmn-at-aol-dot-com Thu Dec 12 14:39:51 1996
> Date: Thu, 12 Dec 1996 12:51:00 -0500
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Frequency calculations
>
> All,
>
> There was a Tesla Math Formulary published on this list on 8-10-95 - courtesy
> of Richard Quick I believe.  I was doing some calculations last night on my
> new small coil and found a problem with equation # 6: Frequency of Coil.  The
> formula given is: F=300,000 / T x W x pi x (.9144 / 36) x 4  where f =
> frequency of the coil in khz, T = number of turns, W = width of the coil in
> inches.
>
> Using this formula, I get a number quite a bit lower (like 40 or 5% lower)
> than I get using wheelers equation, caclulating the self capacitance then
> calculating the resonate frequency .  I have measured the inductance of my
> present coil and the self capacitance and the frequency and know these other
> methods work as they should.
>
> Has anyone else tried using this formula?
>
> Ed Sonderman

Ed,
In Foster's book on elctromagnetics I use the formulae
designed for circular pole antanae. And, Brent turner uses the
same formula in his book. But It's probably a good idea to calculate
your coils parameters ten ways from sunday. Sorry, I have not
used the "Richard Q." equation.

1.75(h/d)^0.2
----------------
(1*10^9)    (Fr*d)        = Nt

h = height of coil
d = diameter of coil
Fr = Frequency your shooting for
Nt = Number of turns

Hope this helps.
D. Gowin
```