23 Nov
1999
23 Nov
'99
1:17 p.m.
At 01:57 AM 11/24/99 +0000, you wrote:
\>There are some people here (you're certainly one, I like to think I'm
another) who (most of the time, at least :-))
understand what we're
trying to look at and understand just what our test gear will do when
given a strange signal. We know what our '20MHz' scope will do with a
30MHz signal. And we know how to push the instruments a bit.
What about diagnosing a fault triggered by excessive "ringing" (say,
because of having substituted a driver by something with a smaller than usual
trise) with an 80 Mhz fundamental? You won't see that in the slower scope...
It reminds me of when IGBT's first came out. The transitions were so
fast that transmission line effects between the power electronics and the
motors sometimes caused a stationary wave -- that tended to break down
the insulation in motors over time. The very first generation of IGBT
AC drives from most companies had this problem -- nobody had thought that
could happen ...