>=20
> hFE doesn't matter much. My DC calculated load is around 350ma @ 12v DC; =
in
> fact, I would be using PWM with variable duty cycle so the current will b=
e
> lower than calculated.
>=20

But if you are only going to use it as a digital switch and make sure that =
it=20
is saturated when on and keeping the switching times as short as possible (=
as=20
short time in the linear region as possible) the power dissipation over the=
=20
transistor will not be very high. 350mA @ around 0.5V saturation voltage gi=
ves=20
175mW (on continuously).

I would probably use a hard driven N channel FET for PWM instead. And would=
=20
probably not need a heatsink either. If it is an inductive load, you might =
want=20
to use external diodes (instead of the internal body diode in the FET) for =
back=20
EMF.

/Ruben


=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124
200 39 Malm=F6 Sweden
www.liros.se
Tel +46 40142078
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.