Just as the model for a power source is a constant voltage source of 0
Ohms in series with some arbitrary value of resistance that is determined by
the makup of the materials in the power supply, a ground can be thought of
as having some resistance hidden away in the resistance of the materials that
make up the circuit.  Since resistors in parallel produce a R(total) that is
less than either of the resistances by themselves, having more than one
ground insures that there will be less possibility for crosstalk between
signals caused by ground loops.  If one ground is good, two are better.

        Circuits that are sensitive to noise such as audio amplifiers and
A/D converters will malfunction if there are ground loops and digital circuits
will even malfunction if the ground loops are bad enough.

        I am not an engineer, but it is safe to say that decoupling of
switching transients is one of the best things that one can do to make a
circuit work as planned and not glitch at the worst time.

Martin McCormick WB5AGZ  Stillwater, OK 36.7N97.4W
OSU Center for Computing and Information Services Data Communications Group

Andre Abelian writes:
>Hi to all engineers.
>
>I just noticed that 16c62a has 2 grounds. what is the purpose of this?