Re: Triggered gap and safety gaps

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

Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>

Marc,

There was probably enough parasitic capacitance to provide a low current
"displacement current" spark, but it might not have enough energy to
consistently trigger the gap. A nice, hot, high current trigger pulse is
what you want to consistently trigger the gap...

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "Metlicka Marc by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>
> 
> bert,
> in my early "RAW" circuit, i didn't provide this return path. i grounded
> the case of the nst, the dimmer case and the nst filter circuit ground
> term., could this have been why the safety gap would fire every once in
> a while? i wondered were the trigger energy was going, i thought maybe
> it was following the main tank energy around the primary?
> i am setting up to try terry's setup now.
> marc m.
> 
> Tesla list wrote:
> >
> > Original poster: "Bert Hickman by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <bert.hickman-at-aquila-dot-net>
> >
> > Jonathan,
> >
> > A path needs to be provided for current to flow for the triggering pulse.
> > This is the trigger return path I was referring to. When using an NST
> > HV source, the trigger return path can be provided via the center tap
> > of the NST. Trigger pulse current flows through C1, the spark gap trigger
> > electrode to one of the main gap electrodes, and back through the NST
> > center tap (via a direct connection per Terry's most recent circuit).
> >
> > However, in the case of isolated secondary HV transformers (pole pigs,
> > radar transformers), you will have to "create" a return path using the
> > circuit I previously provided for Weazle McCreath, See Case 2
> > below.
> >
> >                  ------------            C1
> >         Pri      |          |    HV      | |               to
> >       <----------| Trigger  |------------| |---------->  trigger
> >                  |  Coil    |  Output    | |            electrode
> >                  |          |           30-50 kV
> >    From          |          |
> >   Dimmer         |  Common  |
> >    Ckt           ------------
> >                       |
> >       <---------------o-------------------------------> Ret
> >     Mains                              Case 1: to center tap of
> > NST
> >    Neutral
> >
> >
> >                          Case 2
> >                      Isolated Xfrmrs
> >              (pole pigs, RADAR transformers)
> >
> >                   C2                   C3       R3-R4 = 15 kV Bleeders
> >                   | |                  | |      C2-C3 = 40-50 kV Doorknobs
> >           |-------| |--------o---------| |--------|      (100 - 500 pF)
> >           |       | |        |         | |        |     Use cascaded caps
> >           |                  |                    |      for sufficient
> >           |                  |                    |       HV isolation
> >     H1    |        R3        |          R4        |     H2
> >     o-----o-----/\/\/\/------o-------/\/\/\/------o------o
> >     HV1           15 kV      |         15 kV            HV2
> >   Output          (Min)      |         (Min)           Output
> >                              |
> >               Ret            |
> >                 <------------|
> >
> >
> > Hope this helped!
> >
> > -- Bert --
> > --
> > Bert Hickman
> > Stoneridge Engineering
> > Email:    bert.hickman-at-aquila-dot-net
> > Web Site: http://www.teslamania-dot-com
> >
> >