I need to switch on a couple power supplies with a 5V logic signal and want to do this with a MOSFET (for lower voltage loss than a BJT). The first is 3.3V at 5A max, and the other is 12V at 1A max. But I'm not sure how to design these switches and choose the MOSFETs. Can someone here help me with this design or know of a link that will teach me this. Thanks.