almamater:
How long will the batteries last? (2xAA) +/- ?
Of course it depends on how much use it gets. The circuit goes into power-down mode after five minutes, but I'd guess at least several months with frequent use, could be a year or more with less use. With the power-down logic disabled, i.e. running 7x24, it will run 2-3 weeks on a fresh pair of alkaline cells. (The power-down logic can be disabled by holding the button down while inserting the batteries.)