Good day to all. I've got an interesting question: what kind of performance will I get=20 if I run a PIC from an un-filtered, full-wave-rectified DC supply at=20 60Hz (120Hz)? I have an existing product that regulates temperature using a really=20 simple 2-transistor diff amp (long-tailed pair) and=20 thermistor. Power supply is a simple full-wave bridge rectifier /=20 resistor & zener regulator. Because its tiny, there is no power=20 supply filtering. Performance below PSU regulation is predictable=20 and the units seem to be happy being powered off and on 120 times per secon= d. Now I've been asked to add two more thermistor inputs (all with=20 different set-points) and I'm running out of space on the board (its=20 pretty tiny). There just isn't enough room to fit in 4 more sot-23=20 transistors and associated resistors. My first thought was to use one of the nice, new Silego chips that I=20 started playing with but they contain only 2 comparitors. So: I'd=20 have to use a pair of them. My next thought was to use a PIC. One of the new 10F or 12F parts=20 should work just fine, except for that pesky pulsating DC supply. This would not be feasible with the old PICs - they had that=20 1024-cycle oscillator delay before leaving reset. But the new PICs=20 running from internal RC oscillator should start up pretty quickly,=20 I'd think. I'm currently looking at the 12f1822 and 12f1840 because I've got=20 some here but I may look at the equivalent 10f parts if I don't need=20 all the i/o pins. Opinions appreciated. Many thanks! dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .