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Re: AC Resistance (formerly Spice Simulation Pictures)



At 05:25 AM 11/6/96 +0000, you wrote:
>>>> Subject: Re: Spice simulation pictures
>>>Subject: Re: AC Resistance (formerly Spice Simulation Pictures)
>>>> Subject: Re: Spice simulation pictures
>
>From rwstephens-at-ptbo.igs-dot-netTue Nov  5 22:12:51 1996
>Date: Tue, 5 Nov 1996 12:36:01 -0500
>From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Re: AC Resistance (formerly Spice Simulation Pictures)
>
>>>From couturejh-at-worldnet.att-dot-netSun Nov  3 22:17:33 1996
>>Date: Sun, 3 Nov 1996 05:22:54 +0000
>>From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>>To: tesla-at-pupman-dot-com
>>Subject: Re: AC Resistance (formerly Spice Simulation Pictures)
>
>>At 05:25 AM 10/31/96 +0000, you wrote:
>>>> Subject: Re: Spice simulation pictures
>>>

   Big snip  ----------------------------
>>
>> Bert -
>>
>>Your data did not include the Q factor of your coil. The 82.6 ohms you give
><SNIP>
>>important that this parameter be given extra attention and optimized during
>>the design stage. 
>>
>>Understanding and studying the Reff parameter would give the advanced
>>coilers a means of increasing the spark length and overall efficiency of
>>their coils. It is apparent that as we learn more about the Reff resistance
>>of Tesla coils we can design the coils to produce more output and be more
>>efficient.
>>
>>Jack C.
>
>Jack,
>
>What do you think of this measurement technique?  Take your stand 
>alone secondary and place it in series with a carbon composition 
>potentiometer.  Apply a sine wave from a signal generator at 
>the resonant frequency of the secondary coil under test across the 
>coil-pot series circuit.  With a VTVM of sufficient frequency response, or an 
>o-scope, adjust the value of the pot until the amplitude across it 
>matches exactly the amplitude across your coil.  Now disconnect the 
>pot and measure its DC resistance with an accurate digital ohm meter. 
>This number is your Reff and also your Rac.
>
>rwstephens
>
------------------------------------------

Robert -

That sounds like a good idea. I will have to try it. The R in the equation Q
= X/R has been given many faces in the past. Sometimes it was Rdc and
somtimes Rac but I had never seen an R that would give a Q factor that was
anywhere near what you would find when you tested the coil for Q factor. 

When I saw a graph in Henney's book for Q factors for single winding
solenoid coils I used that and back-figured the R's for the typical Tesla
coil information I had on hand. I will admit it was speculative but I felt
it was better than Rdc or Rac. This method guaranteed the Q factors would
agree with the typical coil. 

I made a graph for what I call the effective resistance Reff and for several
years have been in the process of verifying it. This verification is going
slowly because coilers are not very interested in this parameter. I believe
it is important because it involves overall efficiency, damping factor,
critical coupling, mutual inductance, log decrement, power factor, etc. and
other important Tesla coil parameters.

Thank you for your suggestion.

Jack C.