A question for electronic gurus:
I was thinking about getting another Oncore or similar module and putting together a battery powered GPS module. Basically, because I'm a cheapskate and I'm not going to pay over $100 for a gps module for my pocket pc when I can make one for $40. So my question is related to power, how can I power an Oncore-like unit with batteries? I could get 4 AAs together for 6V, but what do I do to regulate that to 5V efficiently? I don't think the 7805 setup I have in my car would be very kind of batteries. Would the more efficient switching regulators be my only option or is there something else I can do to make that 6V go down to 5 (something cheaper)?