Re: Spark Gap Behavior (fwd)

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Original poster: List moderator <mod1@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Sat, 28 Oct 2006 22:23:06 -0500
From: Bert Hickman <bert.hickman@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Spark Gap Behavior (fwd)

Tesla list wrote:

> Original poster: List moderator <mod1@xxxxxxxxxx>
> 
> 
> 
> ---------- Forwarded message ----------
> Date: Sat, 28 Oct 2006 10:46:59 -0700 (PDT)
> From: G Hunter <dogbrain_39560@xxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Spark Gap Behavior
> 
> Does anyone know offhand how a TC single static air
> gap behaves when conducting? Does it exhibit a fixed
> voltage drop? A fixed resistance? A dynamic voltage
> drop or resistance? Positive or negative
> characteristic? If anyone has the data handy or if you
> can point me at a link, please do.
> 
> Thx,
> 
> Greg
> 
> 
>  
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Hi Greg,

A short, unconstrained (free burning) spark gap in air has a dynamic, 
negative resistance characteristic. As you increase current, the 
effective resistance drops such that the overall voltage drop across the 
gap remains relatively constant. For gap currents of 10 amps or more in 
TC tank circuits, a first cut approximation for a single gap's "on" 
behavior is a pair of back-to-back Zeners in series, each with a "Zener 
voltage" of between ~150-200 volts. The actual voltage drop for a given 
gap will be a function of electrode material(s), spark length, and (to a 
lesser degree) the peak current flowing through the gap. At very high 
currents, the resistance characteristic becomes slightly positive.

Here's a link you may find useful - although it discusses triggered 
gaps, much of the information is applicable to simple 2-terminal gaps.
http://www.reb3.com/pdf/sg_appl.pdf

Bert
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