Re: Best sparks (fwd)

---------- Forwarded message ----------
Date: Wed, 8 Jul 1998 12:12:14 -0600
From: terryf-at-verinet-dot-com
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Best sparks (fwd)

Hi Greg and All,

        I didn't quite have the RC oscillator in mind.  I was thinking how
an active or ringing RC system would look spectrally but not of a proper RC
oscillator circuit.  However, now that you mention the RC oscillator system,
it would fit and make sense.  The arc could easily act as the active
amplifying element to drive this system.  I still wonder if there is some
inductance somewhere that is also contributing but if not, the RC system may
indeed be the mechanism we are seeing. 
	Thanks for clearing up this fuzzy point.  My original post was rather
confusing on this.

        Terry Fritz

At 10:30 PM 7/7/98 -0600, you wrote:
>---------- Forwarded message ----------
>Date: Tue, 07 Jul 1998 09:31:45 -0700
>From: Greg Leyh <lod-at-pacbell-dot-net>
>To: Tesla List <tesla-at-pupman-dot-com>
>Subject: Re: Best sparks (fwd)
>DC wrote:
>> Terry listed an equation regarding the spectral emission from the arc
>> itself.  This equation listed the RC time constant as a source for the
>> generated frequency.  This is incorrect.  RC time constant is a dissipative
>> factor.  It will not store energy like an LC time constant value and does
>> not support resonance, in fact, tends to reduce or oppose any resonant
>> buildup.  
>Actually, Terry's equation is quite valid, and gives the 3dB freq 
>for a given RC circuit.  RC oscillators are actually quite common,
>too much so sometimes for someone trying to stabilize an amplifier!
>Energy storage is not a prerequisite for oscillation;  any gain
>mechanism with feedback shifted 180deg will oscillate nicely.
>Ever hear of a relaxation oscillator?  This is the primary mechanism
>at work in lightning strikes, for producing the whistlers and even
>the multiple strikes.  Anyone who has played around with HVDC is
>familiar with the distinct screechy whistle as a corona reaches out
>to a grounded screwdriver... an RC oscillator at work!
>The 2.5MHz component in Electrum's output power is undoubtedly an
>RC oscillation between the top C and the effective R of the arc
>channel, for the oscillation is quite erratic in amplitude, and 
>therefore very low Q in nature.
>Waveforms available at: http://www.lod-dot-org/electrum/sphere10us.jpg
>[big snip]