I wish to have bi-directional PWM control over a small toy 9V DC motor,
from a PIC 12C509, so I guess I would set up a H-Bridge using four logic
level MOSFETs, but I have a few newbie questions;

a) can I use MOSFETs of the same polarity top and bottom of the bridge?

b) are there any simple tricks I can use to reduce damage in case the
   prototype code manages to switch MOSFETs so as to short the supply?

(This is another Technical Aid to the Disabled project.  For a disabled
child so they can run their toy railroad.  The control unit will receive
a UHF remote control signal as three TTL inputs, a valid transmission
line and two contact closure signals.  One switch will mean go forward,
the other switch go backward, but I don't really want to use relays to
do it; the effect would be far too abrupt.)

--
James Cameron                                    (cameron@stl.dec.com)
Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800