Re: Tesla Coil Blunderbusses

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

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

>  > 
>  > The aim was to see if a change in the quench time would influence how
>  > smoothly the static gap would fire. 
>  > 
>  > The firing of the static gap was very erratic,  and there were certain
>  > bands of breakdown voltages for which operation was regular and others
>  > where it was totally chaotic.  I _eventually_ managed to set the
>  > breakdown voltage so that the static gap would continue to fire if
>  > kicked with an initial breakdown. 

Richie, Malcolm, all,

Your simulation Richie is most interesting.  I have noticed on my
coils, that if I replace the sync gap with a static gap, the coil tends
to run very erratic, which agrees with your results.  This also reduced
the spark length and made the sparks weaker appearing.
>  >   
>  > The mw02.gif file shows exactly the same setup with the conduction
>  > time increased to 150us.  The spark gap is triggered again at 5ms, 
>  > but this time continues to fire smoothly until the end of the
>  > simulation !

>  >> 
>  > I also ran a simulation with a 200BPS sync rotary in place of the
>  > static gap, because I'm not sure what is happening here !   In this
>  > case changing the conduction time from 100us to 150us (or even 200us)
>  > made no significant change to the power throughput.  The peak voltage
>  > actually dropped by around 1% for the later quench.
>  
>  In practice, the rotary is going force firing as the electrodes move 
>  closer together, one reason I expect it works so well. Which means I 
>  *have* to build one.
>   
>  > Personally,  I would not like to say whether this behaviour is really
>  > significant in terms of practical spark performance,  but the
>  > simulation does prove that gap quenching can influence the stability
>  > of a widely set static gap.

I've always had a hard time getting smooth operation with wide-set static
gaps and a low bps.  The only way I can get smooth operation is
to use narrow gaps, but then the sparks are much shorter.  The 
rotary solves all that, and probably a triggered static gap is OK also.
>  > 
>   
>  > I think the decaying performance often reported from overheated TCBOR
>  > gaps may be due to this reduction in firing voltage rather than due to
>  > actual loss of quenching ???  You can hear the gap scream as the
>  > repetition rate increases ???

I think this is definitely true with overheated static gaps.

Cheers,
John Freau

>  
>  > 
>  >        Cheers,
>  > 
>  >        -Richie,
>  > 
>  >        (Newcastle, UK)
>  
>  Many thanks again. BTW - I enjoyed visiting you webpage. I recommend 
>  it to all.
>  
>  Regards,
>  malcolm