Well, untill your post made me check the site again, I was using a 9V battery, but now I'll have to find something else. Using 4 AA's might work, but note that NiCd or NiMh rechargeables are only 1.2V, so 4 of them gives 4*1.2=4.8V. Fully charged they give a little more than 1.2V, so it might work. If you check the list, you can see a column called "Max dropout voltage". This is the voltage you will have to be over the output voltage. I use an MCP1827 which has a max dropout voltage of 330mV, so I have to supply it at least 5.330 V. Note, that this is if I was to draw 1.5A out of it. If you take a look at the datasheet, you can see on the curves at page 10, that if you draw, fx. 250mA, the dropout voltage is 0.05V, which means that it should work with as little as 5.05V input.
