Re: using XC to cancel XL

To: tesla-at-pupman-dot-com
Subject: Re: using XC to cancel XL
From: Bryan St <warp27-at-juno-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Sun, 07 Nov 1999 08:38:13 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme


On Fri, 05 Nov 1999 08:11:13 -0700 Tesla List <tesla-at-pupman-dot-com> writes:
> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net> 
> 
> Hi James,
> 
> > Original Poster: "The Flavored Coffee Guy" <elgersmad-at-msn-dot-com>
> >Here's how to avoid that problem in a small discription,  use a
> >rated spark gap, or a spark plug that you can gap yourself, a
> >diode, and a larger cap.  In the circuit arrangement the order
> >of parts would be as follows: 120 AC, Diode, or bridge rectifier,
> >Filter capacitor, Spark gap, NST.  You can even the control the
> >frequency that the gap fires.  Filter capacitor, Inductive choke,
> >tuning capacitor, spark gap, NST.  Which would be a pi filter,
> >charging a small cap before the spark gap, feeding the NST
> >the same way you would feed the primary of the tesla coil.
> > There are spark gaps, and gaps small enough for 120 volts to
> >jump.  It might take 15, er 20 non-resistor type plugs to do it
> >but, they will work, if you know how to adjust the gap of a
> >sparkplug..
> 
> I don´t think this will work, unless you use some kind of
> resonance trick. Getting any kind of "straight air" gap to
> self trigger under ~300 volts is next to impossible. Secondly,
> even if you get the gap to fire, you will really stress the
> rectifier as the cap discharges into the NST and recharges
> there after. Of course you could design a remote triggered
> "low" voltage gap by pre-ionizing the gap with a shot of HV,
> but I think this is more trouble than it is worth.
> 
> Lastly, I am not sure if this really helps output. It´s more like
> a single shot (even if repetitive) circuit. Charging such a cap
> to a higher voltage than the NST was designed for, will most
> likely lead to increased stress (and heat) in the NST primary
> as the core will start to saturate (which lets the primary
> winding look more and more like a short than an impedance).
> 
> Raising the input frequency of an NST will also result in increased
> losses as the iron can´t follow the increased "beating" properly. It
> might be an idea for a ferrite powered HV supply unit, tho.
> 
> Coiler greets from Germany,
> Reinhard
> 
> 
Reinhard, flavored coffee guy(???)
Oh yeah, I forgot about the saturation in my reply.  Oh well.  i beleive
that the soft iron cores can be run up to around 1khz though so that is
not a problem really.  To prevent overstressing of the rectifiers, the
filter choke should prevent the current surge when the volts across your
gap drop.  with a 35 amp bridge, the cap can be charged to a firing
voltage of say 150 in no time, though motor run caps will be a must.  For
the spark gaps,  two scr's with the right forward breakdown(150v)could be
used in antiparallel.
Bryan


> 
> 
> 
> 

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