Re: TC Criticall Coupling (was Overcoupling?)

To: tesla-at-pupman-dot-com
Subject: Re: TC Criticall Coupling (was Overcoupling?)
From: "John H. Couture" <COUTUREJH-at-worldnet.att-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Tue, 11 May 1999 19:32:56 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

  Malcolm -

  Thank you for the reply. To determine the amplitude of the TC energy don't
you need to measure the amplitude of two parameters plus the time period?

  Energy = Volts x Amps x dt

  To determine the overall efficiency you need the input energy and the
output energy.

  % Efficiency = 100 x Output energy/Input energy  

  If I understand your reply correctly you measured only one parameter and,
therefore, did not have the coil energy.  

  I show how I did this for one of my coils in my Tesla Coil Construction
Guide. I haven't heard of anyone else doing this relatively simple test.
This type of test makes more engineering sense than the random extra long
spark.

 How did you test for "equal amounts of energy are lost" in the Tesla coil
primary and secondary circuits?   

 After 100 years and thousands of coils built and tested the coilers still
do not agree on the proper way to do the TC testing. It's about time for
someone to write a book on the proper testing of Tesla coils. Not me.

John Couture

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

At 10:45 PM 5/9/99 -0600, you wrote:
>Original Poster: "Malcolm Watts" <MALCOLM-at-directorate.wnp.ac.nz> 
>
>Hi John,
>          I'd be happy to explain...
>          
>> Original Poster: "John H. Couture" <COUTUREJH-at-worldnet.att-dot-net> 
>> 
>> 
>>   Malcolm -
>> 
>>   What was the "K" coupling at 90% efficiency? Did you make any other
>> coupling vs efficiency measurements?
>
>Other coils I've measured also do considerably better than 50%. You 
>can measure the amplitude differences between two successive 
>secondary maximums and calculate the energy loss as a percentage
>of total initial energy for two transfers which when divided by two, 
>gives a close figure for the power loss for a single transfer.
>
>>   Are you saying that equal amounts of energy are lost in the TC rimary and
>> secondary circuits at critical coupling (50% eff)? Please explain.
>> 
>>   John Couture
>
>Yes. Terman is referring not to capacitive discharge coupled circuits 
>but to circuits where steady-state impedances are present on both 
>windings (e.g. the IF transformer in a radio set). In an IF 
>transformer, there is a steady power transfer from one fixed 
>impedance to another whereas in a TC, the transfer is a transient 
>one. Additionally, the secondary impedances change markedly with the 
>onset of a discharge.
>
>Malcolm
><snip>
>
>
>