"w. v. ooijen / f. hanneman" wrote:
> 
> > Will a ULN 2803 (8 darlington drivers) protect its inputs from back-EMF?
> > In the case of a PIC driving a 2803 which drives the stepper motor coils,
> > is there any danger of hurting the pic?
> 
> A 2803 has bleeder diodes to the Vcc, which is the only function of the Vcc
> pin. Don't forget to connect it, otherwise things will work normally but
> only for a short time. The bleeder diodes protect the 2803, the circuit
> driving the 2803 won't notice any spikes.

See my comments on this in one of the other posts.

> 
> > Should I stick a 0.1uF or <what value> uF cap on each of the 4 PIC pins?

Never put more than 50pF *directly* on a PIC output - read 
the PIC specs carefully. This may caus e latch-up. If you 
really want to (but I can't see why), add a series resistor 
in first.

-- 
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