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Re: 0.5*C*V*V vaild? (Was Output Voltages and Voltage/Leng (fwd)





---------- Forwarded message ----------
Date: Fri, 13 Feb 1998 20:29:09 +0000
From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: 0.5*C*V*V vaild?  (Was Output Voltages and Voltage/Leng


  All -

  As D C Cox mentions the Q factor of a Tesla coil can be found by using the
method I show in the Tesla Coil Notebook. I have never seen this test method
for Q factor published before. This method  requires an oscilloscope and is
based on the equation

    Q = 3.1416/log dec

  The log dec can be found from the equation

    log dec = ln(a1/a3)

  The a1 and a3 can be found from the waveform shown by the scope and as
shown in the Notebook. This test appears to be the only way to find the Q
factor of a Tesla coil while operating at high voltage. 

  John Couture

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

At 01:28 AM 2/11/98 -0600, you wrote:
>
>----------
>From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
>Sent:  Tuesday, February 10, 1998 11:12 AM
>To:  Tesla List
>Subject:  Re: 0.5*C*V*V vaild?  (Was Output Voltages and Voltage/Leng
>
>to: Ed
>
>As I am sure you are aware, measuring static Q is nearly meaningless with
>regard to dynamic operating Q factor.  John Couture's method of measuring
>dynamic Q by measuring the bandwidth factor is the very best way to do it
>--- and the calculations of Vpri x dynamic Q produce a valid output of
>actual Tesla coil potential.  John's method is detailed in his book and is
>must reading for anyone who really wants to know exactly what their coil is
>producing in terms of potential.
>
>DR.RESONANCE-at-next-wave-dot-net
>  
>
>----------
>> From: Tesla List <tesla-at-pupman-dot-com>
>> To: 'Tesla List' <tesla-at-pupman-dot-com>
>> Subject: 0.5*C*V*V vaild?  (Was Output Voltages and Voltage/Leng
>> Date: Tuesday, February 10, 1998 6:40 AM
>> 
>> 
>> ----------
>> From:  Edward V. Phillips [SMTP:ed-at-alumni.caltech.edu]
>> Sent:  Monday, February 09, 1998 2:16 PM
>> To:  tesla-at-pupman-dot-com
>> Subject:  Re:  0.5*C*V*V vaild?  (Was Output Voltages and Voltage/Leng
>> 
>> "
>> Works by the Corums, particularly the Notes for their program TCTUTOR
>> are fairly complete. Unfortunately, one learns almost nothing about
>> how to build a good coil beyond the basic understanding that
>> thousands of turns of fine wire with a high h/d ratio is not the best
>> idea in the world. I too have serious doubts about what they say,
>> partly because of a total lack of measurement with regard to output,
>> but more tellingly, the reported "measured and predicted Q of 60" as
>> given for an example coil in the 1990 ITS Symposium Notes that I
>> would have expected to clock in with a Q of at least 250 based on
>> coils I have built and measured. Draw your own conclusions about the
>> theory that predicts that result.
>> 
>> Malcolm"
>> 
>> 	You'd really have to work to get the Q as low as 60!!
>> Some "Quickies" I wound up here with about 1000 turns of #30
>> on an UNDRIED 3" mailing tube measure well over 250 at 300
>> kHz.
>> 
>> Ed
>> 
>
>
>