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>

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

Tesla list wrote:
> 
> Original poster: "jpeakall by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jpeakall-at-mcn-dot-org>
> 
> Bert,
> 
> I am not sure what you mean by "return to trigger". Any schematic or
> explaination for us "thickies" would be great!
> 
> Thanks,
> 
> Jonathan Peakall
> >
> > I don't think that kickbacks will be a problem as long as you use
> > relatively small (500 pF) doorknob caps in series with the trigger and
> > return to the trigger coil to serve as blocking caps

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