Re: Coupling Coefficient

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

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Bart and All,

There is a far simpler way to determine primary to secondary coupling.  It
is especially useful for design work where you don't have the actual coils
to measure.  The accuracy is near the few percent error.  It's the method I
always use now:

http://hot-streamer-dot-com/TeslaCoils/Programs/MANDKV31.ZIP
http://hot-streamer-dot-com/TeslaCoils/Programs/MANDKV31.PDF

Of course, it's Dr. Mark Rzeszotarski's wonderful MandK program.  A simple
computer program that lets you input the coil's dimensions and it easily
spits out the coupling numbers for you.  It is very accurate and well
proven.  I have not done an actual coupling measurement since I became
convince how well this program works.

Paul Nicholson also has a UNIX based program that will do it too, but Marks
program is probably the easiest to just load and use.  However, Paul's
program may have better accuracy and more pure science behind it for those
that are super picky.  It is based off the fantastic work at:

http://www.abelian.demon.co.uk/tssp/

So coupling can easily be determined without having to get up out of your
chair :-))

Cheers,

	Terry



At 12:49 PM 12/3/2001 +0000, you wrote: 
Hi CJ - 

Don't let our past thread confuse you. Coupling is the ratio of inductance
the primary and secondary have upon one another (mutual inductance) due to
the fact the coils are in close proximity. Yes, changing proximity by
repositioning primary or secondary does change the ratio of mutual
indutance or coupling (K). 

As far as measuring Mutual Inductance, here's a post from 1997 that as far
as I'm concerned, is still the easiest and as accurate as to the stability
of the current load being used. Of the list below, I have found hair dryers
to apply a pretty stable current at around 10 amps. Let it run for about 1
minute (to stabilize heat coils with output air) and the change in current
will be minimal. Resistors of low value are no good as they heat up and
current changes dramatically. High value resistors don't apply a lot of
current (but it can stabilize well). Heat elements have the same problem as
low value resistors (I even tried a 3000W 10ohm - no good). Hair dryer is
still #1 in my book. 

Terry's 97 post follows. 

Take care, 
Bart 
  

From:   Terry Fritz 
Sent:   Thursday, November 27, 1997 9:14 AM 
To:     Tesla List 
Subject:        Best Method to Find Coupling Coefficient 

All, 
        I have tried all the suggestion I have received (Thanks Malcolm, Fr. 
Tom, John C., Mark Rzeszotarski).  The best method I have found that does 
not require expensive equipment or great theoretical challenges consists of 
the following. 

        Apply a heavy 60 Hz AC current to the primary coil.  This is best 
done by placing a space heater, hair dryer, etc. in series with the primary 
to limit the current to about 10 amps.  Measure this current with a 
multimeter.  Note that the space heater gives a fairly stable resistance. 
snip...