[sdiy] sniffing

[jhaible]

> But how can you build a low cost E field probe?
>
> Perhaps an aluminum ball? Where goes ground in this case?
> Or two balls forming a dipole?

One ball. GND is Earth. Your scope, including the shielded wire
to your E probe, is earth-grounded. The unshielded part that sticks
out of your shielded cable (your aluminium Ball, for instance)
is the E probe.
Actually, you're measuring a voltage to gnd ("Potential" - what's the
English word for this?), not the E-Field, but then again it's the
voltage (caused by the E field), and not the E-field, that affects
your circuits, so you measure exactly what you want to see.

JH.