Re: DC TSG - It works!

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

Hi Steve,

Really neat report--cool news. I'm pleased you got the
TSG to work with the filtered DC supply, because I've
got a choke output DC supply on the drawing board
right now, and have actually taken the first
construction steps. Your report gives me an
alternative to the ARSG.

My question is this: how hot does the annular trigger
electrode get? I'm asking because trigger electrode
heat will influence my TSG design. Does the slotted
holder rod get hot enough melt plastic?

Best Regards,

Greg
http://hot-streamer-dot-com/greg


--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "S & J Young by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>
> 
> Coilers,
> 
> Today I bit the bullet and tried a variable
> triggered spark gap (VTSG) in a
> filtered DC powered TC setup.  It actually worked
> quite well, which
> surprised and pleased me greatly!  I will describe
> the VTSG I built, then
> the interesting results.
> 
> DESCRIPTION:  My VTSG is a pair of 3/16 inch
> tungsten electrodes spaced
> about 3/8 inch apart.  The electrodes are held in
> copper plumbing fittings
> as described my recent posting.  The trigger
> electrode is a 3/4 inch id
> washer centered around the mid point of the tungsten
> electrode gap.  The
> washer has the inside edge sharpened to increase the
> e-field and improve
> triggering performance.  I suppose this
> configuration is a field distortion
> TSG.  The washer is actually a 1 inch to 3/4 inch
> "reducing washer" used for
> reducing the size of a conduit opening in an
> electrical box.  I soldered it
> in a slot in the end of a brass rod which inserts in
> the perpendicular
> electrode holder.  The ring is held at mid-potential
> of the main gap by two
> strings of resistors, and is driven through five
> .001 mF 10 KV caps in
> series.
> 
> Allegedly this sharpened ring configuration should
> perform better than the
> TSGs used by Marc and others which have a third
> tungsten electrode
> perpendicular to the main electrodes.  The annular
> sharp edge is supposed to
> induce multiple spark paths.  I viewed my gap in
> operation through a welding
> glass, and it does appear that more than one arc
> occurs.  Whether I am
> seeing parallel arcs or a series of single arcs
> jumping around, I can't
> tell.  The main arc passes through the ring without
> connecting to it.  This
> is a nice feature as you don't have to worry about
> the trigger electrode
> eroding or melting.
> 
> I drive the trigger ring with a HEI coil driven by
> 12 volts switched by a
> power transistor.  The power transistor is driven by
> a 555 with a fixed
> pulse width of about 1.1 ms.  This width prevents
> the ignition coil from
> saturating and allows high BPS.  This is driven by
> another 555 in a variable
> oscillator configuration.  Actually, the oscillator
> is running at 1000 times
> the BPS, and drives a divide by 1000 circuit.  This
> lets me monitor the
> oscillator frequency with my Wavetec 27XT reading
> KHz instead of Hz.  This
> provides more accurate readings of BPS.  Output BPS
> goes from about 1 to
> 1000 in two overlapping ranges.
> 
> The circuits are posted at Greg's Garage site under
> "Power supply ideas from
> Steve Young".  http://hot-streamer-dot-com/greg/  These
> circuits show a
> two-channel setup - just throw out the stuff for the
> second channel (was
> originally for a SPDT type TSG which didn't work.)
> 
> I couple the output of a small Hoover canister
> vacuum cleaner to a half inch
> PVC fitting spaced close to the gap.  The air blows
> through the gap at about
> 45 degrees to avoid toasting the trigger ring.
> 
> 
> --Steve
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 


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