Re: [TCML] Critical Coupling?

[futuret@xxxxxxx]

 Dex,

I personally don't use the term "critical coupling" to
express the optimal coupling of a SGTC.  I think it can
cause some confusion.  I prefer to use the term
"optimal coupling".  I agree with you that this optimal
coupling value will vary for different coils.

Cheers,
John



 


 

 

-----Original Message-----
From: Dex Dexter <dexterlabs@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Fri, Jan 15, 2010 1:50 pm
Subject: Re: [TCML] Critical Coupling?


Indeed I suspect too  "critical coupling" means 
something different for coilers than in radio theory.
I don't think it stands for "magic k" values either.
I guess you are right and that it denotes  the
highest coupling in practical SGTC designs before
insulation problems are faced.
In Tilbury's book "The ultimate TC design and
construction guide" (pp 108-113) he refers to the
value k=0.2 as the critical coupling.
Quote from the book:
"A dashed line appears at k=0.2 in the worksheet 
graphs and in the figures 4-19 through 4-24 denoting
the critical coupling fot spark gap tesla coils.
The worksheets can be used to design any type of coil;
however,the critical coupling threshold of k=0.2 
applies only to SGTCs."

Frankly,fixing value k=0.2 for all designs of SGTCs
,all primaries and secondaries has got no sense to me.
Moreover,insulation problems also depend on the bang
size.With k<0.1 the insulation problems can be induced
if the bang size gets too large for the coil size and
the various flashovers ,or if you are lucky ,just 
secondary racing sparks will happen.



Dex   




 
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