Actually.... You don't need a '12 volt out'. That circuit has a MOS-FET that switches the power. You just need a 12 volt power supply. That MOS-FET is handling all the power switching for you. In that article there is this picture: http://i.imgur.com/Bbs3Mmg.png

It says at the top of the picture 5 volts. But you can connect the drain of that MOS-FET to 12 volts without any worries. Or more accurately, VDD at the top of the diagram can be 12 volts instead of 5 volts. That MOS-FET is being turned all the way on and all the way off. It doesn't really care how much voltage it is switching. You can just grab 12 volts from your power supply and feed it into that circuit instead of 5 volts.