Quoting Michael Watterson : > Or if consumption is low and intermittent then a MFP1640 off 1 x AA > alkaline to 3.3V may be appropriate. Fantastic ideas, thanks. Consumption should be low, the only function of the circuit is to =20 continuously send an IR pulse with a short delay between pulses. I =20 need to test the exact duty cycles and repeat times, but have so far =20 had success with a 40khz carrier and a 1/3 duty cycle on for the "on" =20 periods (the same as normal IR remote controls). I have never used a boost regulator, but that could be a nice way to =20 make the package smaller by using less batteries (though size is not a =20 primary concern). I especially like the datasheet for the MCP1640, =20 great explanations (although the efficiency graph looks very MS =20 Paint!). Good prices on this part at Farnell too. David --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .