I have a Aalborg stepper motor valve with a built-in control module that has a 0 - 5v Speed pin that I can control from my arduino uno, and a 12VDC CMOS Logic Direction pin that controls which direction the valve is opening or closing (0V or 12V respectively). I'm having issues sending a 5V logic value from the arduino and converting it to a 12VDC CMOS Logic to control the direction. I've tried using an NPN transistor and a Darlington transistor with no luck (emitter output is always 5V when high, collector voltage is 12V). The Aalborg stepper motor valve runs on a 800mA, 12VDC power supply that I would like to tap into. Any suggestions?