Re: Rotary Sparkgap

Hi all,

> >> With say 14,400 volts in at 500 ma how
> >> long does it take to fully charge a .025 mfd capacitor? 
> >
> >By my calcs (using a transformer impedance based on V/I of about 
> >29kOhms) a time constant is about .75mS. 
> [snip]
> >Justathought,
> >Malcolm 
> >
> >
> Malcolm,
>         Has anyone plotted an IV curve for a shunt limited xformer? I know
> just enough transformer math to be dangerous, but my gut feeling is that
> they are not linear at lower currents.
>                                                 jim
Jim, that's a good point you raise. I WAS looking at it from the POV 
of a limited transformer. It's more likely that it's a pole pig with
those specs and therefore limited only by external inductance hung on 
the primary. It may be that the 500mA is the maximum that can be 
drawn without blowing a fuse. If so, my crude impedance calc may not
be valid. It may be that a v. small cap could be charged far more 
often than I suggested.
    And yes, I think you may be right about the I/V linearity of a 
neon. Only one way to find out - I'll try some measurements on mine
this weekend and post.