bananasiong said:
no.. i not talking about the h bridge.. i need to control a stepper motor.
just look at figure shown below.
You've never mentioned a stepper motor before?, you've been talking about a DC motor - COMPLETELY different things!.
You simply need four NPN transistors that will handle the current, and make sure they are turned hard ON.
Have a look at for an example, the transistors are rated at 800mA, and were fine for the stepper I used, which came from an old 5.25 inch floppy drive, and which I simply fed from 5V.