Please help if you can, I need to build a variable voltage DC power supply to power a device requiring 4-10v and draws about .1-.5A. I've looked at all kinds of circuit options (lm317, nte953, darlington pair, 2n3055 NPN, rheostats, etc) and I think i'm just confusing myself the further I get into it. I don't understand the possibility of using the LM317 and a potentionmeter when the power I need supplied is far greater than the 1/2 watt max a common 5k pot can handle... 5v @ 200mA, P=5v(.5A), I have to be missing something with my understanding of pots and voltage dividers... a 1/2watt max of power doesn't seem like much to provide to a device, which is the typical rating of the pots I've seen in the said circuits. If its easier, can somebody please refer me to an alternate method to build my required power supply? I would really like to make sense of this all.