Note the data - in the second (reset) lot i held the thermistor in my hot little paw for about as long as it takes Nurse to take your temperature with the old mercury thermometer.
So if (& it's a Big If, given the uncertainty of the thermistor's provenance) 0.5 is 25 degC, what is 0.575?
After a lot of messing about i've finally tracked down some thermistor data:
courtesy of vishay.com.
umptee pages of stuff, but i eventually found (i think) what i'm looking for..
| RT [Ω] 332 094 239 900 175 200 129 287 96 358 72 500 55 046 42 157 32 554 25 339 19 872 15 698 12 488 10 000 8059 6535 5330 | Temp Deg C - - - - -
-10 -05 0 05 10 15 20 25 30 35 40 |
Yup!! & i even managed to stop Blogger from complaining about my html (well, it wasn't mine, it's just the way the table turned out..)
ReplyDeletebut the info's there & i can muck about with it now..
Now since this is (supposed to be) a 10kOhm NTC thermistor, its resistance will be higher that 10k @ temperatures below 25 Celsius, thus driving the Analog 0 voltage down - which is what i'd expect in a nice warm room @ (i suspect) about
ReplyDelete20 degC: a value just below 50%..
Quick calculation: 12488/22488 = 0.555
Hmmmmm..
..not looking right @ all!
(sigh)
well i tried..
Wait a minute, stupid!!
ReplyDeleteYou're looking at the Wrong End of the divider network!
You want 10000/22488 = 0.446!
That's much better!
That actually looks reasonable!
Recall the values of about 480 in the SM readout?
Maybe the temperature is about 21-22 decC in here..
wouldn't be surprised..
Best get onto the next Task, coz i think i've got this sussed!
That ratio - 575/500 - is about 28.75 (!!)
ReplyDeleteNOT what i expected..
..but there's the Big If, isn't there..