> For analog work you generally want something with dual outputs
> to supply both your postive and negative rails.

I can't think of much apart from audio amplifiers that need amperage
on the -ve rail. Maybe a split-rail motor driver

It's more likely the typical analogue circuit that includes op-amps
will need only a few mA for Vee, which you're better to derive from
something like a diode-capacitor inverter rather than have a whole,
rarely-used, PSU devoted to it. IMVHO.

For example, a 555-based inverter

http://www.reconnsworld.com/forum/read.php?16,8,8

A PIC pin will do this perfectly well too, eg under timer or PWM
interrupt or on demand. At low currents the Vee generated is very
nearly -Vdd

Nothing wrong with a 2 x 30V PSU of course, but you may find
you'll be making little converter add-ons anyway when a circuit
needing 3 or 4 voltages presents itself

Joe
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