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Re: another version of frequency formula

    To: tesla@grendel.objinc.com
    Subject: Re: another version of frequency formula
    From: EDHARRIS@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
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    ; Tue, 16 Jan 1996 08:39:53 -0700

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

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