Mitchell - the two things I know about a hexfet that makes them better than
a transistor is 1)there are versions that only require 5 v to turn them on.
This makes them a snap to connect directly to a PIC to handle large power
loads of any (reasonable) voltage.  2) A hexfet (or any FET) has a very low
resistance when "turned on".  I do not remember the exact figures, but I
think a transistor may have an internal resistance in the range to 10's to
100's of ohms.  A hexfet may have a resistance on only 1ohm down to .006
ohms.  The more resistance present, the more energy that is converted into
heat that must be dissipated, plus it is wasted energy.

So the bottom line is, hexfet's are easy to interface and energy efficient.

David V. Fansler
Network Administrator
TripPath Imaging, Inc.  (formerly AutoCyte, Inc.)
336-222-9707 Ext. 261
dfansler@autocyte.com
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Updated December 16, 1999
Ann's Cancer & David's Observatory



                -----Original Message-----
                From:   Mitchell D. Miller [mailto:mdmiller2@HOME.COM]
                Sent:   Tuesday, December 28, 1999 4:23 PM
                To:     PICLIST@MITVMA.MIT.EDU
                Subject:        Re: stupid question about sink/source

                > "Use HexFets, not bipolar transistors"

                What's special about HexFets?

                Mitch Miller, Omaha, NE
                mdmiller2@home.com