At 05:33 PM 9/4/2004, M. Adam Davis wrote: >Can anyone suggest a suitable diode to drop 0.9v, or an alternative method >for cheap, low to no power consumption voltage drop from 3 AA or AAA cells >to 3.6V? > >It consumes less than 4mA in active mode. I don't want to add any extra >active components due to power consumption and cost. How much current when idle? I think you might be able to use a single hi-gain transistor connected as a diode or, barring that, add the two resistors that make up a "Vbe multiplier". But it depends upon how much current your circuit consumes while idle. diode connected transistor (2n4401): A= C&B, C= E. Should be pretty close to 0.5 .. 0.6V drop over uA - mA. Vbe multiplier: 2n4401 transistor. Bat+ to C and to top end of 22k resistor. Bottom end of resistor to B and to top end of 47K resistor. Bottom end of resistor to E and to load. Load is assumed to be at least 15 uA - add a load resistor if needed. May not work anyways - expect to see some drop when load becomes active. Silly little non-zener regulator: same as above except that bottom end of 2nd resistor connects to gnd instead of to E - pick resistor values such that you lose about 0.3V across 1st resistor. Should be able to make this one work but with the cost of 20 - 50 uA quiescent drain. Might be worth a try - shouldn't cost more than a few minutes to see if any of these works. Note that the temperature performance of all of these is abysmal (same as your original approach using a diode). dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 20 years of Engineering Innovation (1984 - 2004) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist