Convert 3.3v to 14v?
You will need to use a boost convertor. For best efficiency, you'll want to use a dedicated boost IC, rather than spin your own. It's not the best in performance, but I like the LM3578 for use by inexperienced people. It's adjustable, and the output voltage is set through a pair of resistors. As long as you put a reasonable LC network (see the datasheet) on the output and use a Schottky diode, it will regulate. It's also available in a DIP package for easy prototyping.