Re: solid state simulation

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>



Tesla list wrote:
> 
> Original poster: "Kelly & Phillipa Williams by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <kellyw-at-ihug.co.nz>
> 
> Hi All!
> 
> While thinking about computer simulation of the primary circuit, I wondered,
> why can't you do that for real? (putting two back to back zener diodes in
> for the static spark gap was not my idea, I read it on this list ;-)

Almost.. 

The problem is the power dissipation in the zeners.. The voltage across the
zener will remain high, while the current flows, dissipating I*Vz watts...
A spark gap, on the other hand, once it breaks down at several kV, the
voltage across it drops down to a few tens or hundreds of volts, so even
though it is carrying many amps, it isn't dissipating much power.

Also, a spark gap is a thermally conductive massive device, and the very
high peak power (albeit short lived) isn't as important as the average
power.  The tiny bond wires and junction in (even a big) zener are more
sensitive to peak powers (their thermal time constant is very much shorter).

There are several semiconductor devices that has the bistable behavior of a
spark gap: thyristors (SCR, TRIAC) and Tunnel diodes are two.