Re: triggered gap update and question

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

Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-uswest-dot-net>" <mystuffs-at-orwell-dot-net>

duncan, jim, jon, all

Tesla list wrote:
> 
> Original poster: "Dr. Duncan Cadd by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>
> 
> Hi Marc, Jim, All!
> 
> >i have been trying to get my triggered gap that is setup inside the
> >pyrex tube to fire by field distortion, i'm using the setup posted by
> >bert hickman and i'm using the 1/2" wide hard copper strip from the
> back
> >of a CRT of a television for the trigger electrode.
> >the strip is wound around the outside of the tube, 1 1/8"dia in a
> spiral
> >and i haven't had any luck getting it to fire regularly. <snip>
> 
> If you have practical difficulties putting the electrodes in the tube
> as per Jim's suggestion, you might try winding a full circle outside

no i've successfully ground a nice slot in the side of the tube (1/8"
thick) with a cupped "green" wheel. with the trigger electrode inside
the tube it works fine, it actually was to easy to build and it works TO
well, kinda took all the anticipated fun out of it? i am just goofing
around with different setups for future knowledge sake, i thought that
if i could get it to fire with a outer trigger ring it might lead to all
kinds of things?



> the tube directly over each internal electrode and connect the two
> circles to your trigger source.  If you look at a lot of U-shaped
> flashtubes, you'll see that the trigger electrodes there are wound
> outside the glass directly around the electrodes fused into the glass,
> so that there is ionisation between the internal electrode and the
> trigger applied to the outside of the glass.  The ions then migrate
> internally within the flashtube, but these things are of course at low
> pressure (a few mmHg) and I don't know how effective that will be with
> your setup.  It might be physically easier to try as a "quickie"
> though before attempting to stick electrodes inside the tube.

the ring i'm trying was placed center around the gap, i think, as jim
wondered, with the 1/8" of glass and .340" to the edge of a main
electrode, it is just to far away. i could get it to fire without the
air sucking through the tube, but only at about 60hz, no mater where i
placed the ring, it wouldn't change.
i'm starting to think maybe only one half of the wave would give the
right effect to fire the main electrodes? why this would be is beyond
me.


> 
> Another idea would be to extend the diameter of the internal
> electrodes e.g. with a bit of aluminium foil or copper wire or a thin
> metal disk/washer (it won't be carrying heavy current so the material
> shouldn't matter) so that the distance between the trigger electrode
> outside the glass and the main electrodes inside is reduced and also
> so that there is a kind of "point" on the inside electrode aimed at
> the external trigger electrode to promote ionisation.  I'd just be a
> little concerned that you may in that case be liable to get the main
> spark punching through the glass if you make the distance very small,
> EHT at rf likes to do things like that :-(

yes, i wanted to get the main gap arc to travel from anode to cathode
without the jumping too and from the trigger electrode. i know it sounds
like i'm trying to reinvent the wheel by building a vacuumish triggered
gap, but since the trig. electrode through the tube idea can be made
inserted into a piece of 1 1/2" pvc pipe very easily and a muffin fan
could be used to draw air through for a good, cheap, easy to make medium
powered sync. triggered gap.
i thought, why not try it with an external electrode? this would give a
relatively "dark" firing spark gap, leaving all the light coming from
the
streamers with no distraction.
plus it's proving to be a challenge with fun involved.
thanks,
marc


> 
> Dunckx
> Geek#1113 (G-1)