Re: Pig Ballast measurements
>From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
>Subject: Re: Pig Ballast 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.
I've been there and done that before, just not at these voltage
levels, so I'm not sure how to quantify how much of this is ground
> 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.
Yep, just try to look at a "TTL" signal with a 1ns rise time (1GHz+)
with a 10cm scope "ground" lead some time. Worse yet, try to run that
signal .3m around a circuit board as a system clock. I've had circuits
where the ringing on the clock line was enough to cause multiple
"clocks" per cycle, and would work as SOON as a 10Mohm 5pF scope probe
was placed on the line;(
That was not even in the same league as 6nf -at- ~~20kV dumping it's
energy (1.2j) into 3 meters of inductive wire with a negative
resistance element to boot! Until I get this solved, I'm not even
going to look at my TC primary.