Oscilloscope question

[Tony Duell]

> 
> >  Are there any good web sites that 
> > would give some basic info on "scopes for dummies"
> > or "scopes for beginners"?
> > 
> 
> 1) Turn on 'scope
> 2) Dwiddle random knobs till you see squiglly lines
> 3) Nod knowingly...

Argh NO!

You'll get a trace that way, but it may well not be meaningful.

I once helped a studnet doing a practical on an LC series circuit. I 
think he was looking at the phase relationship between the applied 
sinusoidal voltage and the voltage across the capacitor. And he couldn't 
get any sort of sane results. IIRC he saw almost no phase change at all.

He was using a standard (albeit cheap) modern double-trace 'scope, which 
would have been quite capable of doing what he wanted. But he had one 
control set wrongly. He got a trace, but it wasn't meaningful.

OK, what was he doing wrong. Some of you will get this instantly, I think...

Rememebr 'It is much rasier to make measurements than to know what you 
are measuring'

-tony