Re: electrode distance for stationary spark gap

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Blake Hartley <teslaspud@xxxxxxxxx>

When I said to pull the gaps in a little I meant exactly what Gary
said about set it so it barely sparks. Sorry for the the confusion.

Cheers,
Blake


On Mon, 07 Feb 2005 08:29:35 -0700, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "Lau, Gary" <gary.lau@xxxxxx>
>
> Sorry, but I'm compelled to point out that this is bad advice.  Running
> a coil with the gap opened up to the point where it won't fire is like
> putting your car in neutral and flooring the gas.  Even if it does fire,
> it may be at a voltage far higher than is safe.
>
> A static gap acts like a voltage clamp, limiting how high a voltage the
> capacitor will be charged to.  It's not immediately obvious, but this
> voltage can build far higher than the rated secondary voltage of the
> transformer.  If the cap is not discharged through the gap, the voltage
> will build higher and higher on each mains half-cycle, through what's
> called resonant rise.  The transformer secondary and the tank cap form
> an L-C circuit, resonant in the neighborhood of 60 Hz.  Most folks these
> days strive to use a cap value larger than what would be mains resonant
> (i.e. LTR - Larger Than Resonant), but transformer core saturation and
> ferro-resonance may conspire to achieve mains resonance none the less.
>
> The only safe and reliable way to set a static gap is to apply only the
> transformer across the gap (i.e. no cap in the circuit) and set the gap
> width to just fire.  OK, maybe slightly wider if you like to live on the
> edge.  As others have pointed out, there is no simple table that will
> correlate gap width and voltage for any arbitrary geometry, especially
> when using multiple gaps in series.
>
> Regards, Gary Lau
> MA, USA
>
> > Original poster: Blake Hartley <teslaspud@xxxxxxxxx>
> >
> > Chistopher,
> >
> > I have started with two bolts that you can unscrew to make the gap
> > larger. Start with a small gap and hook up the power supply,
> > increasing the gap until there are no sparks, aand then pulling them
> > back in a little. Even though this works, you are probably better of
> > using a couple of pieces of copper pipe to form a multi-gap.
> >
> > Cheers,
> > Blake
> >
> >
> >  > I am trying to figure out how you determine how much of a gap
> distance
> >  > between two stationary electrodes should be? For a stationary spark
> gap. Is
> >  > there a formula ? All responses are appreciated :)
> >  > Thanks
> >  > Chris
>
>