Re: Gap Firing Characteristics (was Re: Tesla Coil Blunderbusses)

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi John,
         I think you're right:

On 11 Apr 01, at 16:03, Tesla list wrote:

> Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <FutureT-at-aol-dot-com>
> 
> In a message dated 4/10/01 8:48:15 PM Eastern Daylight Time,
> tesla-at-pupman-dot-com writes:
> 
> > After 
> >  being inspired by a piece from Scott Myers on how he improved the
> >  output of his coil, I eventually got around to building a larger
> >  oblate topload for the coil. Secondary Fr went from about 155kHz to
> >  130kHz, a figure which serendipitously allowed me to add a single
> >  turn to the primary to maintain tune, boosting primary inductance
> >  by about 50%. (Aside - the primary ringdown showed an enormous
> >  reduction in losses). 
> >        Up until the mod was done, the gap work smoothly with no 
> >  airblast. Following the mod and with the gap in no way altered,
> >  operation was totally erratic. Much messing around failed to get it
> >  running smoothly. At that point, I started running a jet of air
> >  through the gap and through much adjusting of the airflow and gap,
> >  got closer to good operation but still very erratic. It would fire
> >  in bursts of half a second to a couple of seconds and then just
> >  stop. 
> 
> Malcolm,
> 
> Yes, I can see how (as you suggested [or partly suggested],
> in your other posting), if the large toroid delayed the breakout, or
> even prevented it at times, this would delay the quench, and also
> affect the cap charging, and may have prevented the gap from firing at
> times. I have found in my work that larger toroids hurt the quenching,
> (but increased the spark length nevertheless).
> 
> I wonder if the coil would have benefited from a sync rotary gap, or
> even a triggered gap.
> 
> John Freau

This is exactly the situation where a rotary is going to win over the 
static since the electrodes are forced to get close enough at some 
point in the charging cycle. Totally agree with what you say.
     I may get an opportunity to look into this over the weekend. Not 
the rotary since I don't have a satisfactory one running at present 
but the problem itself. Many thanks for commenting. 

Regards,
malcolm