# Re: another version of frequency formula

• To: tesla-at-grendel.objinc-dot-com
• Subject: Re: another version of frequency formula
• From: EDHARRIS-at-MPS.OHIO-STATE.EDU
• Date: Tue, 16 Jan 1996 10:39:51 -0500 (EST)
• >Received: from phyas1.mps.ohio-state.edu (phyas1.mps.ohio-state.edu [128.146.37.10]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id IAA00187 for <tesla-at-grendel.objinc.COM>; Tue, 16 Jan 1996 08:39:53 -0700

```A
>
>The above formula does not take into account the coiling of the wire.
>Written in similar terms to the above, the formula I posted becomes:
>
>	  c                                 (1/5)
>F = ------------------------ x (5/4) x (H/D)
>     4 x length of winding
>
>
>c=speed of light
>H=height of coil
>D=diameter of coil
>
>Nothing special. Just highlights the difference due to coiling the wire.
>For an H/D=10, the two forms differ only by a factor of 2.
>
>
>SOrry to beat a dead horse.
>-Ed Harris
>
>
>Ed,
The length of wire as measured in what units? Inches, feet, meters ?

Jim Leonard
---------------------------------------------------------------------
Jim,

The one nice feature of the above formula is that you can use
whatever units you want as long as they are consistent. For H and D all you
need is the ratio which of course is unitless. If you choose the speed of
light as c=3x10^8 meters/sec, then choose the length of the winding to be
in meters so that the frequency will come out in Hz=1/sec. Alternately, you
could choose the length of the winding in miles and c=186,000 miles/sec and
still get the frequency in Hz.

Eg. as Mark B. reported, his giant coil has the followinf dimensions:

H=11ft
D=4ft
length of winding= "about one mile"

186,000 mile/sec                       (1/5)
F= -------------------- x (5/4) x (11ft/4ft)
4 x 1 mile

F= 71000 Hz

This is close to the self resonant (no top electrode) frequency he
reported (correct me if wrong M).

As I said before, it works well on all the coils I have made as well as all
the coils Malcolm so gernerously reported on.

-Ed Harris

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