Re: max L with given length of wire

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 10/25/02 8:04:37 PM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:



>
> R = 1.1111*B
>
> Note: This result is in close agreement with that
> found in “Electrical Engineers’ Handbook , Electric
> Communications and Electronics,Edited by Pender and
> McIlwain, copyright 1936, John Wiley and Sons Inc. 
> which states that the ratio of the diameter to the
> coil length should be 2.45 for maximum inductance


Three Comments:
1)I fail to see how 2.22  ~= 2.45 is "in close agreement" in any but the
crudest of approximations.
2) The Mike Hollingsworth derivation of maximum inductance seems to be almost
verbatim from that shown by Duane Bylund in his book "Modern Tesla Coil Theory"
published about twelve years ago.
3) I demonstrated in a paper last winter (sent to the Geek Group) that, for a
given wire length and given pitch there is a unique spiral with maximum L and a
unique solenoid with maximum L. It also appears that for optimized coils at T
turns per inch, L(spiral)~=T*L(solenoid). 
I will be forwarding a copy of that paper to terry-at-hot-streamer-dot-com within the
next few minutes. Hopefully it will be posted and I would appreciate it if
someone would check it for computational mistakes. (I'm not infallible, but
don't tell my grandkids).

http://hot-streamer-dot-com/temp/MaximizingInductance1.doc

Matt D.