4. I don't think these are logic-level FETs...?
Otherwise could someone tell me what the Vgs(th) actually is? I know it's the threashold but what is the practical implication if you still need a 10 V Vgs?
You have to look at the graphs in the datasheet to see the actual minimum gate voltage to support higher current conditions.
http://www.irf.com/product-info/datasheets/data/irf3205.pdfIf you check figure 3 you have Id = 30 A @ Vgs = 5V, that is what tripping me off a bit. If you needed saturation current (or similar) then a minimum power should be stated. Or am i totally missing the point?
Actually, I found a solution using a CMOS NAND Gate as a 10V or 12V Driver and Vcc to the NAND chip.