Re: Pig Ballast measurements

To: tesla-at-pupman-dot-com
Subject: Re: Pig Ballast measurements
From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
Date: Wed, 10 Jul 1996 17:37:51 +1200

Hi Jim,
       Some observations....

> >I changed scales to look at the "60Hz" output voltage. about 28kV with
> >occasional 75kV peaks! Yes I check this 3 times. No wonder I'm
> >seeing/hearing  such a difference between resistive and inductive
> >ballast!
> >
> I expected at least some scepticism from someone. Is everyone on
> vacation?
> 
> I'm not sure that I believe the 75kV peaks myself!
> 
> Would anyone with a scope, HV probe and ballasted transformer please
> double check some of my measurements.

Firstly, the small tuned circuits formed from small chokes with their 
low self-C, short paths and low capacitances can be rung up quite 
easily to those levels with the energy available from the primary 
cap and the transient shocks provided by the spark gap.
     Secondly, you can't always believe the scope. When is a ground a 
ground? I have observed the most horrendous overshoots in digital 
circuitry earlier in my career (careering?) which could be traced to
long scope ground leads, stray L's and C's formed BY the scope 
connection etc. Tricky indeed.

Malcolm