VAX Cluster on Ebay in OK (was Re: More DEC equipment spottedin

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Tue May 4 22:53:35 2004

> > There is no such thing as ground!.
>
> Sure, there is. It's the voltage potential present on a long electrode
> inserted into the earth. :)

And just what do I connect the other lead of my voltmeter to? :-)

Incidentally, 'There is no such thing as groud' is one of Voanda's laws
and has 2 meanings. The first is the one I am using there, that
voltmeters have 2 leads, and it's arbitrary where you connect the
'refernce' lead to.

The second is that any real connection has impedance, and that the
'ground' in a high-speed digital circuit may not be quite the same
voltage everywhere. In fact 'ground bounce' -- mostly due to the
inductance of the ground connection -- is a problem in laying out high
speed circuitry.

-tony
Received on Tue May 04 2004 - 22:53:35 BST