hi. my AN8002 just arrived. i bought it mainly for its temperature function (beside its probe accessories that i will use for my UNI-T clip probe). to validate reading of my VC99 multimeter. but they are contradicting, when VC99 read 27degC, the AN8002 read 30degC. do you have way to verify temperature reading? i'm not sure which one is faulty VC99 or the AN8002...
You buy a 12 euro meter to calibrate the temperature function of an other meter ?
A good temperature meter has a real thermocouple input (those flat connectors) with a good cold junction compensation. A good thermocouple alone cost more then the Aneng. Calibration grade TC's cost more as the VC99.
Your idea is a bit like buying this meter to validate the voltage reading of a 6,5 digit benchmeter
To calibrate a thermocouple or a multimeter that uses one really good , they use things like a drywell . A device that can make temperatures from f.i. -20 to +120 C. There is often a 3cm hole in the top to enter the thermocouple. But if you use it like that you get not the good values. (It can easy be 2 degrees off) So a 10k costing device will be as usable as the aneng if used not the proper way. To get good results they enter an insert with a hole that is a snug fit for a thermocouple and sometimes they fill up the rest of the space so no air can come in. And that way you can get it within 0,1 degree or better. To get it better as 0,1 they use calibration grade thermometers instead of the one build in the drywell.
You need to calibrate both the TC and the meter.
If have 10 TC's you have a big chance they all give a different temperature. The worst TC I have is over 10 degrees wrong, the best one I have is 0,2 degrees off . I have the luxury of having acces to a lot of calibration gear. I have a simple calibrator my self (Beamex TC303) but I repair calibration gear and 2 of my customers are into temperature calibration so if I get a drywell here for repair I use it to check my TC's (they sometimes include a calibration thermometer so I can check it after repair) You can use it to check your meter and the TC as a combination. But then you do not know if the meter or TC is wrong. So if you want to swap TC's you need a calibration thermometer with TC input or a very good voltmeter. The latter often lacks a good TC input but the Anengs TC has banana jacks so you will never get it better as 1 or 2 dregrees.
You can do a simple test. Put the meter in the refrigerator and let the TC stick out but put it in something with a high thermal mass like a bottle of water so airstream has no influence. First measure the water with the meter outside the fridge, let it stabilize for 10 minutes or so (the connectors and DMM busses also have a seebeck effect.
Then put the meter in the fridge with the TC and bottle outside the fridge. A very good meter with cold junction compensation will not change the readings.
For those interested:
http://schneiderelectronicsrepair.nl/?p=467 a teardown of a simple TIC based drywell that had 3 bad TIC's (peltier elements)
You can calibrate the meter itself with a voltage. There are tables that specify the voltage thermocouples generate. (the TC from the aneng is a K-type) But you need a very stable source and good high resolution calibrated multimeter to check the voltage or use a voltage calibrator. The signals are mV's. That way you now if the meter is correct. You can check the TC too with a voltage measurement. But you need a very good DMM for that too
You can use things like ice-water but that is to check the TC and DMM as a combination. You do in that case not know if the meters read different, if it is the TC or meter.
The Aneng reads a temperature without the TC so it seems to have a some form of CJC.
They probably calibrate the meter with a voltage.
About body temp, that will not work very well unless you know your body temp. Mine is very low (around 35 degrees C) My wife bought an ear thermometer. Used it on my son but it did read very low, she tested it on me, same reading. So back to the shop but the replacement did the same so I took a meter to check and it turned both our temperature was in the 35 degrees. We never had a fever, When I was really sick my temperature was around 37 degrees and you do not measure it if your not sick. . Now I know that is for me like 39 degrees for most people
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