On Aug 15, 2008, at 6:16 PM, der Mouse wrote: >> The power plane? That board has two planes (power and ground). Why >> is one always the reference? > > In low-voltage electronics, there is no such thing as a voltage in > isolation; voltage exists only in reference to somewhere else. > > In high-voltage electrostatics work, there is an absolute reference, > that being "electrically neutral", as in "having equal amounts of > positive and negative charges".
It's still relative. Take an electrically neutral object, place it in an electrostatic shield. Raise the shield potential to a billion volts above your reference point. The neutral object is also now at a potential of a billion volts above your reference point. John Doty Noqsi Aerospace, Ltd. http://www.noqsi.com/ [EMAIL PROTECTED] _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user