RE: More Coupling...

["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>


All -

The test shown below for the mutual inductance was also shown in the Tesla
Coil Design Manual Fig 33. The test used a lamp which is non linear and was
replaced by a resistor in later versions. However, the non linear
characteristic of the lamp is not a factor when the test is made in the
recommended way. The meter then reads directly in microhenries of mutual
inductance.

The K factor can then be easily calculated. This test has been checked with
the JHCTES Ver 2.3 results and the two agree very closly. There are other
interesting TC tests shown in the book.

John Couture

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

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Wednesday, December 13, 2000 7:39 PM
To: tesla-at-pupman-dot-com
Subject: Re: More Coupling...


Original poster: "Ed Phillips by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<evp-at-pacbell-dot-net>

Tesla list wrote:
>
> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <tesla123-at-pacbell-dot-net>
>
> Hi Ed,
>
> Measured K on my flat primary for my 12.75" x 45" coil.
> The flat primary is 16.5"ID, 0.375"wire, 0.625" spacing (c-c) (or 0.375
> edge to edge), and 11.6
> turns in the case of using my 0.06uF cap setup.
>
> I used a method of measuring I believe Terry posted a couple years ago.
>
> Measured current of primary using a hair dryer in series (10.95A). Then
> measured secondary
> voltage (secondary + 1uF cap + 18k ohm in series) at 2.59V.
>
> Mutual Inductance M = V / (377 * I) or 2.59V / (377 * 10.95A) = 627.4 M
>

	That's a perfectly valid and exact method.


> K = M / sqrt(Lp * Ls) = 627 / (107.13uH * 87.6mH) = 0.205 K
>

	Surprised it's that high.  Will have to try a similar measurement here
using a small flat primary I happen to have.


> Anyway, that's K on that day. I am only aware of one program that calc'd K
> but it was
> preliminary and I haven't heard anything about it in a "long" time.
> Measuring is pretty easy and
> can be done with a simple DMM.
>
> Bart

Ed