> When does ripple cause problems?  Will a rippled (rippling?) input
> cause a problem with PICS?  More specifically, let's say I'm using
> a PIC to blink LED's or control a small stepper motor.  Would this
> be a problem?

Well, you wouldn't want to use a rippling supply as Vref, and you'd
need to be sure that ripple doesn't exceed Vdd max. If you're unsure
about the charger (if it were me I'd put it on the scope with various
loads to see what the o/p really looks like), buffer it with a reservoir
cap, perhaps with a series resistor and/or diode. Or even a zener to
clip anything over 5V1

LEDs shouldn't present too much of a problem but a stepper will
probably put noise on Vdd, which can upset logic/reset pins. That's
where the R-C-ZD above can help to isolate the PIC's Vdd from
the raw charger V the stepper is using

BTW, I had a PIC board come back to me for repairs the other day.
It normally runs on an automotive 12V battery but had been hooked
up to a car battery charger (basically a transformer and diode). The
average DC o/p was in spec but regulator and PIC were toasted, so
don't under-estimate ripple

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