"Retro Repair" key electronics skills?

tony duell ard at p850ug1.demon.co.uk
Tue May 10 10:27:55 CDT 2016

> > 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.


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