Hi JJ. My only concern is seesoe's base resistor and his orientation of his base diode. I think he would be better off changing the resistor to 1K and using the diode in shunt mode. Many current PC's (especially laptops) don't have serial ports so USB/Serial converters have to be used. These converters only produce a swing of -5 to +5V.I wasn't quite sure with that, but I thought that the TIP120 wouldn't get saturated at 5V and 1.2A load without a driver. Anyway, now its ok at 1.2W.