On Thu, 1 Mar 2001 20:46:15 -0000, you wrote:

>Hi!
>
>>>I am driving a stepper motor -with 3 windings (4 Ohms each) and
>>>1 common terminal- salvaged from an old disk drive by means of
>[...]
>>>explained by means of the electric power formula :
>>>   W =3D V**2/R =3D 12**2/4 =3D 36W !?!?
>
>That=B4s the whole power you are sinking from the supply. As the 2003 is=
 an open collector transistor, when it is driving the windings the =
voltage across it is about 0.2 volts,=20
>so the power the transistor is disipating is V*I =3D 0.2*3 =3D 0.6 W
Wrong, the 2003 is a darlington, which will drop at least 0.6V,
therefore it will get VERY hot at 3A.

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu