[Prev][Next][Index][Thread]

Re: How to rise the secondary? (fwd)



---------- Forwarded message ----------
Date: Tue, 14 Jul 1998 21:21:38 +0000
From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: How to rise the secondary? (fwd)


  Malcolm -

  What you are saying contradicts what theory says and that is that coupling
only changes the time of energy transfer and not the amount of energy
transferred.  

  However, the scope should show coupling as a change in the half cycles
timing and tuning as a change in the amplitude of the waveform at the end of
the transfer. Do you see this on the scope and how does it correlate with
the K coupling and tuning changes that you are making?

  John Couture
  
----------------------------------

>---------- Forwarded message ----------
>Date: Mon, 13 Jul 1998 15:34:54 +1200
>From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: How to rise the secondary? (fwd)
>
>Hi John,
>          Some points raised by this post:
>
>> Date: Fri, 10 Jul 1998 05:47:05 +0000
>> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>> To: Tesla List <tesla-at-pupman-dot-com>
>> Subject: Re: How to rise the secondary? (fwd)
>> 
>>   To All -
>> 
>>   Why are coilers building Tesla coils and raising the secondary to make
>> them work properly? Raising the secondary of a properly designed and tuned
>> coil only reduces the output. Why use a faulty design of excessive
>> overcoupling then try to correct it by raising the secondary?
>
>It would be too bad if one ended up with a less than optimally 
>coupled design though.
>
>>   If a proper pri/sec clearance is maintained to prevent flashovers 
>> and the
>> coil properly tuned raising the secondary is unnecessary. Tweaking is part
>> of the tuning process and not necessary for coupling selection with a
>> correct design. With a properly designed TC the quenching adjustments relate
>> only to the primary circuit. Quenching always occurs after the first
>> transfer when the secondary circuit has almost zero energy and has no effect
>> on the primary circuit.
>> 
>>   Critical coupling is the same for Tesla coils as it is for any dual
>> coupled RCL system. If this condition can be determined at the time of
>> design the correct amount of overcoupling can be determined and excess
>> overcoupling avoided. It does not make engineering sense to deliberately and
>> incorrectly design a coil with excessive overcoupling and then try to
>> correct it by raising the secondary.
>
>I think it does if one doesn't know the characteristics of the gap 
>one is using or one wishes to experiment with different types of 
>gaps. In a sense, adjusting k for optimal quench and output is 
>"tuning" the system to suit the gap.
>
>>   I have studied and researched this problem with over a dozen coils. My
>> conclusion was that raising the secondary was not necessary with a properly
>> designed TC. In fact a TC that requires raising the secondary can never be
>> adjusted to produce optimum output. This is because moving the secondary
>> away from the primary will reduce the output.
>
>I beg to differ. If transfers do not go to completion (as they won't 
>if k is not one of the loss-adjusted magic values), then raising the 
>secondary could well improve peak voltage production.
>
>> I have not solved the problem
>> of finding the exact coupling for a particular TC. However, coupling is not
>> critical as it does not affect the amount of energy transferred. Only
>> sufficient pri/sec clearance is required to prevent sparkovers. I agree more
>> research is needed.
>
>I think coupling does affect the amount of energy transferred. If it 
>is set between two of the magic values (again, loss-adjusted) then 
>transfers will not go to completion. One can see this on the scope.
>
>Malcolm
>
>