RE: Space winding question

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

Original poster: "John H. Couture by way of Terry Fritz <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>



Malcolm -

You are talking about a different problem. The wire gauge has nothing to do
with the the spacewound 16.7 TPI as long as the wire gauge is not to big. If
it is too big the JHCTES Ver 2.3 shows a
group of stars to indicate to the designer that he has made a mistake in
logic (the program maker must think of everything)!   The TPI must be
coordinated with the gauge and the insulation thickness to give an overall
thickness of

      TPI = Turns / Overall thickness

I believe that this is a problem with Bart's great program as I mentioned in
another post. I haven't checked this out completely but was waiting for
Bart's comments. The rest of his program gives the same answers as mine but
Bart's has more information.

The coil length is always equal to the TPI times the number of turns. This
is what makes the special type of problem I mentioned difficult for experts
using manual calcs (many variables changing at the same time). This problem
requires many repeat calcs of the type Terry showed. For example "With 10
TPI how many spacewound turns of any size AWG wire that is not too large
will have the resonant frequency of 138.67 Khz (same as closewound)? The
answer is 1075 turns and the coil length is 107.5 inches equals 1075
turns/10 TPI. This is an iterative type problem. Can you think of the other
iterative type problems that the JHCTES can solve easily?

John Couture

------------------------------------


-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, March 11, 2001 2:11 PM
To: tesla-at-pupman-dot-com
Subject: RE: Space winding question


Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<m.j.watts-at-massey.ac.nz>

Hi John,

On 11 Mar 01, at 13:00, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <couturejh-at-worldnet.att-dot-net>
>
>
> Stan -
>
> As Terry showed in another post your question can be answered with a
> few manual calculations. However, it is easier to use a TC computer
> program like the JHCTES program. An on-line Ver 3.2 of this program
> can be found at my web site
>
>    http://home.att-dot-net/~couturejh
>
> For your question enter in the secondary inputs
>    Rad       6.00
>    Turns     1000
>    TPI       18.5   1000/54  (closewound)
>    Sec term     0
>    Click "Calculate" or "Calculated etc." and the resonant operating
> frequency of 138.67 Khz appears in the upper right corner of the
> screen. To print click on "File - Print".
>
> For the space wound coil change only the TPI to 16.7 = 1000/60
> Click "Calculate" which gives 140.62 Khz
>
> Terry's resonant frequencies are slightly different because he used a
> different Medhurst equation for the coil self capacity.
>
> There is another type of question that is much more difficult for the
> expert to answer but is easily answered by using a computer. The
> question "How many turns would be required on the space wound coil to
> give the same resonant frequency as the closewound coil?" This
> requires an iterative type solution and "many many" repeat manual
> calculations. Several of the variables are changing at the same time
> including the coil inductance, coil self capacity, etc.

That actually depends on whether you maintain the same height and
diameter or not - i.e. use two different wire gauges leaving all else
the same.

Regards,
malcolm