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>

Gary and all,

You are indeed correct - triggered gaps like fast risetime HV pulses for
best triggering action - adding inductance in the path will be
counterproductive. In the previously provided schematics, the HV Doorknob
capacitors provide appropriate low frequency isolation on BOTH sides of the
secondary of the trigger transformer while passing the fast trigger pulses
to the triggered gap. Personally, I'd use 40 kV doorknob caps or similar to
provide adequate voltage standoff.

Some other excellent sources for information on triggered gaps include C.
P. Clare (check out the High Energy Devices Section, and the paper "AN-135:
Use of Triggered Spark Gaps"). C. P. Clare's site is at:
http://www.clare-dot-com/home/home.nsf/products/

Another great source is the "Technical Brief on Spark Gaps" that's also on
the Perkin Elmer site. Discussion of the various modes of operation and
triggering circuitry are presented, along with some typical circuits.
Triggered vacuum gaps are also covered for the more adventurous.
http://opto.perkinelmer-dot-com/Downloads/switchtb.pdf

Finally, some of the best applications notes are at Marconi's site -
Marconi recently bought EEV, one of the premier suppliers of spark gaps and
vacuum tubes. There are two papers (called Spark Gap Preambles), one for
two electrode gaps, and the other for three electrode (triggered) gaps.
There's another a Preamble on thyratrons that's extremely good for those
looking at the possibilities of using thyratron switching.
http://www.marconitech-dot-com/sparkgap/2elec_sg.pdf
http://www.marconitech-dot-com/sparkgap/3elec_sg.pdf

Enjoy!

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

Tesla list wrote:
> 
> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
> 
> With regard to using an inductor in series with the HV trigger electrode - I
> recall reading advice in an application note to minimize the trigger cable
> lead length (i.e. locate the transformer as near as possible to the gap) so
> as to minimize capacitive loading on it, this to achieve the highest
> possible trigger-pulse rise time.  I suspect that adding an inductor will be
> counterproductive to this end.  The Perkin Elmer web site has some good info
> on this, see http://opto.perkinelmer-dot-com/library/papers/tp10.htm (but I
> can't seem to locate the specific advice to minimize lead capacitance).
> 
> Looking at the circuit configuration for the trigger circuit, it sure looks
> like HV transients will be coupled through the trigger transformer and
> ultimately to the mains lines.  This looks like a very good place to add
> some MOV's and EMI filters.
> 
> Gary Lau
> MA, USA
> 
> >Original poster: "Metlicka Marc by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <mystuffs-at-orwell-dot-net>
> >
> >mike,
> >i have used the coil\dimmer circuit for quite a while now and i haven't
> >noticed any kind of kickback from this circuit?
> >some things i have tried is put two wraps of each mains lead through a
> >ferrite toroid and one turn of the hv trigger lead around a flyback
> >core, whether it helps?
> >if you're worried about the mains, i haven't seen any problems myself.
> >maybe as more coilers try it, more info will come in?
> >if you don't feel secure in using it, please don't, safety relies on
> >sureness.
> >marc
> 
> >>
> >> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <CHURCHMON-at-aol-dot-com>
> >>
> >> Hi Johnathon and list ,
> >> I too am concerned that if I build one of these triggered gaps that I
> could
> >> get back
> >> lash from the tank circuit if I come in contact with the dimmer knob.
> >> Has any one else experienced any from these type of trigger circuits ?
> >>
> >> Thanks ,
> >> Mike Church(CHURCHMON)-at-aol