I just tested my circuit and it's using up 40mA @ 5V (LEDs at a fairly dim level).
Suppose I had a 5V battery rated at 2500mAh, does that mean my circuit would last ~62.5 hours? (assuming 5V is constant)
Would I double the circuit life (to 125 hours) by adding two 5V, 2500mAh batteries in parallel to get 5000mAh?
Switch-mode power supplies (SMPS) are rather sophisticated circuits and no place for the beginner or amateur with no experience. I would NOT recommend something that crude to power a sophisticated load like an Arduino. First off, that circuit lacks any sort of feedback. It appears to operate open-loop ("full-blast")
Would using the previous circuit I showed, along with two AA batteries as the input voltage, meet my circuit's power requirements? Or would it be best to just go with the MAX756? (It seems like the MC34063A needs a minimum input voltage of 3V while the MAX756 only needs 0.7V)