Something I've done which works really well is this:

If I need to sink a medium-current sort of load to ground,
I use a ZTX849 NPN transistor (Zetex, great part!) and
put a series LED in the connection between the PIC pin
and the base of the transistor. This seems to work
adequately for most kinds of loads, though you'd probably
want a 10K base/emitter resistor to handle leakage currents
for very light loads.

The LED provides an extra 1.5-2 volts of drop, and *I don't
use a base resistor at all*. I rely on the PIC's natural
current limiting, coupled with the couple-or-three volts of
LED and Vbe that I've already got out there. As an added
bonus, I get a visual indicator of whether it's 'on' or not.

Mark G. Forbes, R & D Engineer  |  Acres Gaming, Inc.    (541) 766-2515
KC7LZD                          |  815 NW 9th Street     (541) 753-7524 fax
forbesm@peak.org                |  Corvallis, OR 97330
http://www.peak.org/~forbesm
mforbes@hq.acresgaming.com

"There has been an alarming increase in the number of things I know nothing
about."
---Anomalous