Dear "Jose S. Samonte Jr.", Chris Cox may be on to something. Chris Cox on 2001-04-12 11:01:25 AM wrote: > armpit temp(a remarkably stable temperature ... > The curve "shape" ... > Does it mimic an RC time constant? Yes, take a bunch of data look at the graph. It always takes about 7 time constants to settle within 1 part in 1000 -- because ln(1000) is roughly 7. In particular, if, hypothetically, the human armpit had a time constant of 1 minute, then when it is cooled by a 10 K transient, it will take about 7 minutes to settle to within 0.01 K of the final value. Do you see the same response when you warm your probe up slightly above body temperature before measuring ? Since human body temperatures normally change throughout the day (Is that the ``circadian rhythm'' ?), I would much rather use a fixed reference. I know several people who test their thermocouples by dropping them in icewater, which is always very close to 0 C. Maybe you could try sticking your probes to the outside of a metal can of icewater. (Or would plastic more closely emulate a human body ?) -- David Cary -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads