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Re: Electrum output impedance (fwd)
---------- Forwarded message ----------
Date: Mon, 13 Jul 1998 07:17:01 -0600
From: terryf-at-verinet-dot-com
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Electrum output impedance (fwd)
Hi Dr. Resonanace,
Rl is the load resistance (impedance). The "l" is a lower case L. This is
not the dc resistance of the inductor. Perhaps it should be changed to
Rload for clarity.
Terry
At 09:31 PM 7/12/98 -0600, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Sun, 12 Jul 1998 00:42:46 -0600
>From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Electrum output impedance (fwd)
>
>to: Terry
>
>Neat equation. Does RI = resistance of inductor in this post??
>
>DR.RESONANCE-at-next-wave-dot-net
>
>
>----------
>> From: Tesla List <tesla-at-pupman-dot-com>
>> To: tesla-at-pupman-dot-com
>> Subject: Electrum output impedance (fwd)
>> Date: Saturday, July 11, 1998 10:33 PM
>>
>>
>>
>> ---------- Forwarded message ----------
>> Date: Sat, 11 Jul 1998 14:30:41 -0600
>> From: terryf-at-verinet-dot-com
>> To: tesla-at-pupman-dot-com
>> Subject: Electrum output impedance
>>
>> Hi Greg Leyh and All,
>>
>> I was studying the scope photos of the Electrum at:
>>
>> http://www.lod-dot-org/electrum/electrumspecs.html
>>
>> In another post (TC Output Impedance Matching) I propose that the
>> "Load Match Point" in a Tesla coil occurs when the load on the coil is
>equal
>> to the following equation:
>>
>> Rl = 2 * pi * SQRT ( Ls / Cs ) = 195k ohms
>>
>> For the Electrum:
>>
>> Ls = 0.130 H
>> Cs = 135 pF
>> Xls = 31K ohms (the reactance of the secondary at 38kHz)
>>
>> So the Load Match Point (or Tesla point) calculates out to 195k ohms.
>>
>> By knowing the current to the sphere, the frequency, and the inductance
>of
>> the secondary, the voltage at the top terminal can be calculated as 1.55
>> million volts in the 100, 20, and 10 uS pictures. By dividing the output
>> voltage by the sphere to arc current, the arc impedance can be estimated
>as
>> follows:
>>
>> In all cases the 50 amps in the secondary multiplied be the reactance of
>31K
>> ohms gives an output voltage of about 1.55M volts.
>>
>> 100uS Io = 15A Zarc = 103k ohms
>>
>> 20uS Io = 5A Zarc = 310k ohms
>>
>> 10uS Io = 8A Zarc = 194K ohms
>>
>> You will notice that these numbers average out very close to the
>> calculated value of 195k ohms. I suspect that the arc may begin at the
>> 1.55M volt level but the voltage quickly reduces to ~750k volts and
>matches
>> the arc impedance. I don't know if the coil finds this point naturally
>or
>> if the Electrum was designed to operate this way. The close match of the
>> Electrum to these calculated numbers is obviously very interesting!
>>
>> All the best,
>>
>> Terry Fritz
>
>