Re: Best sparks (fwd)

---------- 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]