RE: New formula for secondary resonant frequency

["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>


Kurt -

What are you using for the Medhurst equation?

John Couture

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-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Saturday, February 03, 2001 9:06 AM
To: tesla-at-pupman-dot-com
Subject: Re: New formula for secondary resonant frequency


Original poster: "Kurt Schraner by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<k.schraner-at-datacomm.ch>

------------------------snip


ing of the equation coefficients in the last digits. As a
next, 4 of my own coils are compared:

Coil      Sk B&W	Sk Long Coil	Sk 12cm Coil	Sk 20cm Coil
turns     821		1950		921		979
h         1.768	1.41		0.585		0.68
d         0.4013	0.1633		0.1207		0.2
b         0.7		0.5		0.2		0.5
awg       17.162	22.053		22		22

Fres,cal  131.4	157.3		409.0		209.3 Paul's formula
Fres,exp  119		147.7		368		202.7
Diff      10.4%	6.5%		11.2%		3.2%  cal-exp

Fres,cal  123.1	139.6		372.9		200.0 Wheeler/Medhurst
Diff      3.4%		-5.5%		1.3%		-1.3% cal-exp

It seems, my coils are yet more happy with Wheeler/Medhurst,
however the precision of the experimental data have to be
considered. Regarding the instruments, I believe to be quite
precise (specifics can be supplied). The most of error probably
stems from the spacial situation, present, when measuring the
coils: capacitive influence of the surroundings! The B&W coil,
i.e., was tested in my living room, which is one floor above
ground level, and the top of my big coil only ~0.4m from the
ceiling.

BTW: Would you have perhaps at hand, a version of your function
 = -94.6683*awg*awg*awg + 9000.55*awg*awg - 301175*awg +
3.64056e+6
beeing currently a function of awg, made a function of wire
diameter instead, like f(wd[m])? Measured values of wire diameter
could more easyly be introduced that way.

Hope,the tables will arrive in a well readable condition!

Greets
Kurt Schraner

----------------------snip
-
> Paul Nicholson,
> Manchester, UK.
> --