The Joule-thief (http://en.wikipedia.org/wiki/Joule_thief) is a small self-oscillating circuit which circuit which can use nearly all the energy in a battery. I've seen some posts (eg, http://www.picaxeforum.co.uk/showthread.php?14547-Joule-Thief-powered-PICAXE) discussing how a Picaxe can be powered off a Joule-thief in order to boost the the voltage from 1.5v to well above the minimum operating voltage, thereby both allowing operation from a single 1.5v cell, and using almost all the power from the battery.
But if my primary goal is to simply use almost all of the stored energy in the battery, is there really much to be gained by using a Joule-thief circuit, rather than just using a 3 cell holder? Since Picaxe chips seem to operate down to 1.8v or lower, they will function until the cells are at 0.6v each; this is *well below* their initial 1.5v state. Of course this doesn't have the neat voltage booster effect of the Joule thief. But when a cell is at 0.6v, how much energy remains that could still be harvested by the Joule-thief circuit?
But if my primary goal is to simply use almost all of the stored energy in the battery, is there really much to be gained by using a Joule-thief circuit, rather than just using a 3 cell holder? Since Picaxe chips seem to operate down to 1.8v or lower, they will function until the cells are at 0.6v each; this is *well below* their initial 1.5v state. Of course this doesn't have the neat voltage booster effect of the Joule thief. But when a cell is at 0.6v, how much energy remains that could still be harvested by the Joule-thief circuit?