> I recently picked up a number of 2N5192's surplus and would like to use
> them to construct an H Bridge motor controller (controlled from a PIC of
> course).  The motor I will be driving will draw around 1.5A.  My power
> supply is a 12v 5A battery.  The problem (if I read the datasheet
> correctly) is that the "Collector-Emitter Saturation Voltage" of the 5192
> is specified as Ic=1.5Adc, Ib=0.15Adc.  As I understand this, for my
> Collector-Emitter current to be the 1.5amps I need to drive the motor, I
> need to drive the Base with 150mA. Is this correct?
        <snip>

Not necesarily.  Those figures were just the condition under which Vce was
measured.  The transisitor may have enough gain to saturate at a lower base
current.  The Hfe (gain) figure that you'll find on the data sheet should
give you a reasonable idea.  Hmm...just found it...HFE minimum = 20.  1.5/20
gives a minimum base current of 75mA.  I guess they doubled it to make sure
:o)  Still too much for a PIC to drive directly.

Also, an H-Bridge would normally use 2 NPN and 2 PNP transistors configured
as common emiters.  You *could* use all NPN's with the upper pair working as
emiter followers but I wouldn't personally recomend it.  If you're set on
making a bridge instead of buying one ready made, then think about using
Darlington power transistors or MOSFETs, both of which could be driven
directly from a PIC pin.

Regards

Mike Rigby-Jones