> I got a Honeywell Q313 series "750 millivolt Powerpile Generator" > and have measured it's output when in one finger of a gas stove > flame. > It puts out about half a volt at 100 ma with a 5 Ohm load (50 mw) > and probably would produce more power with a lower resistance load. > See: http://www.pacificsites.com/~brooke/batt.shtml#Heat > > Is there a circuit that would transform this into say 3.3 volts at > 10 ma that would be suitable to power a PIC? Yes. But if you are trying to use the heat rather than trying to use the specific device you may be better off using a Peltier 'cooling' module. These produce substantially more voltage (due to having more thermopiles in series)(and possibly the pile you have uses lower voltage but more robust thermopiles). Using the present module will be a challenge due to the low voltage. Not hard, but easy to be inefficient. Several boost converter topologies will work. A simple flyback converter would be an easy start. Inductor in the drain of a FET. Pulse FET on and then off and coil "rings" to a higher voltage. Coil resistance needs to be lowish. FET needs to be low Rdson, or if a bipolar transistor is used it needs good low saturation voltage. Care needed with all tracks etc to minimise losses. The circuit will almost certainly need to be operated from a higher voltage supply - probably from the output that it supplies. Starting a circuit using silicon components on 0.5 volts is approximately impossible. However, on no load the pile probably makes at least the claimed 750 mV and may make more. Even that is challenging and using an external higher voltage for starting makes the job much easier. A self oscillating converter with a couple of transistors could probably be implemented but an IC based one would be easier. You could use one of the single-cell converter ICs but a package of CMOS inverters would probably do as well. RM -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist