Jose: RE Creeping thermistor end curves... Plot the curve from your armpit temp(a remarkably stable temperature found most anywhere people gather, provided they're not having religious/political discussions) and see how close it matches an RC charging curve with various values. The curve "shape" could represent an infinite number of "mathematical" resistor/capacitor values, or maybe just one or two. Is the temp shape congruent with/very-close-to, some charging curve? Does it mimic an RC time constant? After reading your question and concern about the time it takes, I'm getting suspicious that it may. Which brings up some interesting questions for QED students. Of course, the stable arm pit temp is only guaranteed after you have kept your unclothed arm compressed against your body for at least ten minutes. The minute you open your arm to place the probe all bets are off and your curve now represents two variables: A somewhat cooled armpit, now creeping back up to temp, and the probe response being masked by it. If you wish to use your armpit as a constant, rig a probe attached to a piece of string and slip ONLY the string between your arm and bod, NOT the wire leads to the probe. They transmit heat. (Yes, we're being persnickety but this IS an experiment, right?) After about ten minutes probe and body should have stabilized as much as you can expect. Keep the probe on about 20 centimeters of string out BEHIND you so you don't breathe on it, and away from the body. The rest of the string is in front to pull the probe with. Take your initial measurement and then pull the probe into your armpit area and start plotting. Now, on a more practical note. As long as a skin temp probe indicates about 80-90 percent of it's final value (that's creeping very slowly by now) in say 30 seconds, the med types will be very happy. How long do your 409AC's take? The docs don't really care that a probe is all the way to it's last itsy-bitsy Planck value. An RC curve doesn't REALLY continue to charge for ever and ever. It gets bogged down in all the QED noise at the end and the final value has to start following ambient conditions. What the meds want to know 30 seconds from that hastily placed skin probe is: is that temp 102F or 105??????? 102.4 slowly going to 103 may be interesting. 105 will have everybody jumping... Chris Cox (Another Chris, don't confuse the two of us.) "Jose S. Samonte Jr." wrote: > > I only got the thermistor probes as samples, for my school project. > They are from YSI. They are skin thermistor probes, with part number, 409AC. > > Thank you so much sir Chris. > I also hope that you would help me with my problem. > Best regards. > > Chris Carr wrote: > I have only been half following this thread so my apologies if this > information has already appeared but what is the manufacturer and part > number of the thermistor or what does it look like, size, packaging etc. > > Regards > Chris > > Hello, sir Peres! =) > > The current is 200uA. I try to display the temperature data on an LCD, but > the > reading takes more than 10 minutes to be stable, meaning the change is very > little. Why is this so? > > "Peter L. Peres" wrote: > What is the current in the thermistor, what is the dissipated power in it, > how do you measure it, and how do you define 'stabilize' ? > > Peter > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > ____________________________________________________________________ > Get free email and a permanent address at http://www.netaddress.com/?N=1 > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > ____________________________________________________________________ > Get free email and a permanent address at http://www.netaddress.com/?N=1 > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads