+/- ~2° on Thermocouple Normal?


 
J

J. Rican

TVWBB Member
The best I can get the thermocouple I purchased to behave is bouncing around between +/- 2º of reality every second, sometimes it deviates 3º but it also lands on the right temp or within 1º.

I've messed with changing the ofsets and mV/C but the jumpy behavior seems to follow. I seem to recall reading "a thermocouple is a thermocouple" so I went with a cheapo. If buying a better one is the recommendation I'm ok with that. Or maybe that is just how these behave?
 
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ok, it seems accurate at 5mV/C with -5 offset.

I took the terminals off and plugged the wires into the HM and it looks like that might have gotten rid of the erratic readings...
 
The TC I bought from Auber works great but I did have some problems with the supplied plug. Once I reconnected it properly, it has worked flawlessly. Always check those connectors, I think they are the week link. How is that new WSM working? Congrats on that bad boy.
 
Yeah, in hindsight I should have checked that before posting. Thank you, it hasn't even gotten dirty yet! The aftermarket door and my probes just got here today so it's going to be a long smoking weekend! I'm really excited.
 
When you made the -5 offset, what temperature were you calibrating the probe at?

The AD8495 TC amp should have linearity error of less than ±2°C, within the specified operating range (0°C to 50°C Ambient Temperature Range), (−25°C to +400°C Measurement Temperature Range)
 
The TC on the HM won't read properly down to 32F. You need to calibrate it at 100C boiling ( 212F )
 
Yup! As Steve said you may have noticed it dropped to a certain point and stopped there. This is the lowest temperature it can read and is definitely above 32F. See the Thermocouple calibration section for properly calibrating at boiling temperature.
 
It is right on the money in boiling water w/o the offset. Should have searched the documentation, my ignorance in thermometers didn't realize that the regular probes and a thermocouple would need to be calibrated differently.

Really appreciate you guys taking the time to help out, especially with things that I'm sure seem silly from your perspective.
 
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