Re: Triggered Gaps

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

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

One can CERTAINLY build one's own triggered gap.. there is ample literature
on this list as to how.

All spark gaps will self fire at "some" voltage.  Typically, one designs a
triggered gap so that the gap is long enough that it doesn't fire at the
voltage found in your circuit, but will do so when you apply the trigger
pulse.

A suitable triggering circuit would be an auto ignition coil driven from a
"dimmer" kind of circuit.  The auto coil has a really high output impedance,
so you don't need to worry about feeding your primary power back through it,
although, if you have money to burn, you could capacitively couple it,
adding a couple resistors to bias the trigger electrode.


----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, November 16, 2002 12:05 PM
Subject: Re: Triggered Gaps


 > Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dhmccauley-at-spacecatlighting-dot-com>
 >
 >
 >  > I think I would like to modify my SRSG coil into
 >  > one that uses a triggered spark gap .. thus
 >  > making sort of solid state.
 >
 >  >>>>>>>>>>>Not really.  Not even close to solid state.
 >
 >  > My understanding of the triggered spark gap is that
 >  > it is a single two electrode static gap with the
 >  > electrodes placed at such a distance that they will
 >  > never arc on their own at the desired arcing voltage.
 >
 >  >>>>>>>>>>>Actually, triggered spark gaps will all self-fire at a
specific
 > voltage.  They also tend to
 >                          self-fire during a voltage-reversal.
 >
 >
 >  > In order to facilitate an arc, a third electrode is
 >  > introduced. This third electrode delivers electrons
 >  > from a completely isolated HV circuit into the space
 >  > between the primary electrodes and thus triggers
 >  > the main spark. Kind of like an ultra high power, high
 >  > voltage, low resistance, fast transistor.
 >
 >
 >  > Seems easy enough to build, has anyone made one, if
 >  > so, how did you drive the third electrode such that
 >  > it promoted gap breakdown at the right times?
 >  > (peak and troughs of the NST AC sinewave.)
 >
 >  >>>>>>>>>>>>>>Well, you're not going to build a triggered spark gap.
They
 > must be purchased.  However, you can build the
 > drive circuitry quite easily and set to trigger on a TTL or similar
signal.
 > Basically, you need to build a high voltage pulse circuit as
 > triggered spark gaps can require up to 15kV or more to actually trigger
the
 > spark.  This is usally done with a high voltage capacitor (say 400VDC)
 > and triggered via a cascading SCR scheme.  The 400VDC capacitor (or
similar)
 > would then discharge through a pulse transformer to trigger
 > the gap.
 >
 >
 > Dan
 >
 >