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Re: loose coupling

Subject: 
        Re: loose coupling
  Date: 
        Sun, 23 Mar 1997 07:20:46 +0000
  From: 
        "John H. Couture" <couturejh-at-worldnet.att-dot-net>
    To: 
        Tesla List <tesla-at-pupman-dot-com>


At 04:15 AM 3/17/97 +0000, you wrote:
>Subject: 
>        loose coupling
>  Date: 
>        Sun, 16 Mar 97 09:06:38 UT
>  From: 
>        "Robert Davis" <Davis_Lewis-at-msn-dot-com>
>    To: 
>        tesla-at-poodle.pupman-dot-com
>
>
>Hello, I am new to the list and am in the process of designing and
>building my first (small) coil and have a couple of questions.
>
>  I am a little puzzled as to why Tesla coils should be loosely
>coupled.  Is 
>this due to the high turns ratio (for the extra voltage gain, although,
>as I 
>understand it most of the voltage gain is due to the Q of the secondary
>at 
>resonance) resulting in a high secondary inductance compared with the
>primary 
>or that the degree of flux linkage between the primary and secondary
>should be 
>low for some reason?
>
>  I have also found difficulty in finding a good book on Tesla's work,
>could 
>anyone recommend a suitable title.
>
>
>Thank you in advance, I look forward to receiving your reply(s).
>
>Rob Davis.
>
>-----------------------------------------------

 Bob -

 A Tesla coil does not have to be loosely coupled to operate. Tesla
operated
his coils in both the tightly and loosely coupled modes. 

 A Tesla coil can operate in the trnsformation (tightly coupled ) or
resonant (loosely coupled) modes. In the tightly coupled mode the
secondary
voltage is equal to the primary voltage times the turns ratio. In the
loosely coupled mode the secondary voltage is equal to the primary
voltage
times the Q factor. There are several other equations for finding the
secondary voltage shown in the Tesla Coil Design Manual. 

 In order to operate in the resonant (loosely coupled) mode the Tesla
coil
must be in tune. To be in tune the primary RCL circuit must equal the
secondary RCL circuit. If a Tesla coil does not work it is normally
because
it is not in tune.

 Because the tuning is of prime importance in the operation of a TC, a
computer program should be capable of keeping the system in tune when
changes are made. The JHCTES TC computer program automatically keeps the
system in tune when any changes are made to the input parameters. 

  John Couture