Re: Recycled: Measuring Coupling Coefficients

To: "'Tesla List'" <tesla-at-poodle.pupman-dot-com>
Subject: Re: Recycled: Measuring Coupling Coefficients
From: Tesla List <tesla-at-stic-dot-net>
Date: Fri, 28 Nov 1997 17:05:46 -0600
Approved: tesla-at-stic-dot-net


From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Friday, November 28, 1997 12:46 AM
To: 	Tesla List
Subject: 	Re: Recycled: Measuring Coupling Coefficients

At 01:11 AM 11/27/97 +0000, you wrote:
>
>From: 	Thomas McGahee[SMTP:tom_mcgahee-at-sigmais-dot-com]
>Sent: 	Wednesday, November 26, 1997 6:58 AM
>To: 	Tesla List
>Cc: 	terryf-at-verinet-dot-com
>Subject: 	Recycled: Measuring Coupling Coefficients
>
>> 
>> 
>> From: 	terryf-at-verinet-dot-com[SMTP:terryf-at-verinet-dot-com]
>> Sent: 	Tuesday, November 25, 1997 4:23 PM
>> To: 	Tesla List
>> Subject: 	Measuring Coupling Coefficients
>> 
>> Hi All,
>>         I have been playing with measuring coupling coefficients lately.  I
>> was just wondering if anyone has a relatively easy way to accurately measure
>> this elusive factor?
>
>
------------------------------------------------------  snip

>Here's a recycled post that may be of some help to you
>or maybe some other coiler who is seeking to determine K.
>
>Hope this help.
>Fr. Tom McGahee
>
>From: 	Edward V. Phillips[SMTP:ed-at-alumni.caltech.edu]
>Sent: 	Friday, August 08, 1997 2:50 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	Re:  Mutual Inductance and Coupling Measurement
>
>	Here is a pretty fundamental way to measure the mutual
>inductance, provided you have a millivoltmeter.  Feed a known
>60 cycle current (say power line in series with 100 watt light
>bulb) through one winding and measure the induced voltage
>across the other.  Suppose, for instance, that the mutual
>inductance is 100 microhenries.  This represents a reactance
>of 0.0377 ohms at power line frequency, so the voltage will
>be omega x M x I = 377 x 100 E-6 x 1 =37.7 millivolts.
>	Having measured M the coupling factor k is the 
>mutual inductance M divided by the square root of L1 x L2,
>where L1 and L2 are the winding inductances.
>Ed

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

  All -

  If you need a wiring diagram of how this test is made there is one in the
Tesla Coil Design Manual. In this wiring diagram the components are chosen
so that the millivolts are the uh of mutual inductance and no calcs are
required. It is also safer because low voltage is used.

  Note, however, that this test is at 60 HZ and may be different at the
operating frequency of Tesla coils.

  John Couture