> > Remember one of Don Vonada's laws 'Digital Circuits are made from > > Analogue Parts' > > That's an interesting saying.
Maurice Wilkes (as in EDSAC) once told me 'A digital circuit is like a tame animal. An analogue circuit is like a wild animal. Every so often the digital circuit decides to go back to the wild' :-) Another of Don Vonada's laws is 'There is no such thing as ground'. This has 2 meanings. The first is the obvious one that a voltmeter has 2 leads and it is up to you to choose a reference point to measure voltages with respect to, The other is that, as I said before, any ground connection has impedance (it's the inductance that is troublesome normally) so that points (say IC pins) that are shown as grounded may actually have a voltage difference between them. -tony
