OK, no projects with actual components? OK I guess that happens sometimes.
As for my remark about trolls, there have been a couple in the past who kept wanting more explanations even after really good ones had been given. Hence my skepticism.
I have fought drifting and noise and beat them each time, although sometimes it was a real challenge. So my comments about ground loops are based on experience. Sometimes it is hard to get panel builders to wire things properly because it is more complicated. Those are the times when it makes sense to release drawings with not just the circuit but also the wiring details. It is always faster and cheaper to do it right the first time.

 

LOL then you had better luck than I Bill. I can't count how many times on a job site when asked questions about details that I would say "It's on the drawings, where are you drawings"? Only to be told, "Back in the shop". Our guys invariably did it how they wanted and to hell with the drawing. Which usually meant they got overtime fixing their problems...

 

The IDE i am using on my arduino is 1.8.13 and Arduino Uno Rev 3

 

OK, no projects with actual components? OK I guess that happens sometimes.
As for my remark about trolls, there have been a couple in the past who kept wanting more explanations even after really good ones had been given. Hence my skepticism.
I have fought drifting and noise and beat them each time, although sometimes it was a real challenge. So my comments about ground loops are based on experience. Sometimes it is hard to get panel builders to wire things properly because it is more complicated. Those are the times when it makes sense to release drawings with not just the circuit but also the wiring details. It is always faster and cheaper to do it right the first time.

Yeah Thanks very much .... for the help to everyone who is puting in effort i appreciate

 

Those boards do not look completely different to me. The Adafruit board follows the reference design closely. Excluding the voltage regulator on the Adafruit board, both boards have about the same number of passive devices. It's a very simple design.

I do not find your results for "jumping around" too impressively excessive. Air currents can cause that much difference. You may want to skip the next paragraph and go to experimental results.

Some things to check, which you probably have already done:
Let's assume you have triple checked the voltage supply and your supply is stable and regulated. Do you have the red TC wire connected to negative? (It might be a good habit to use yellow instead of red for + in the design you show.) Did you scrape the TC leads a little before connecting? Are the screw contacts tight? Is your TC the correct one? Is the junction welded?

Your experimental results:
1) Shield both the PCB and TC from air currents. I put a little piece of soft insulating foam on top the IC chip. I did not encase the chip as it probably produces some heat too.
2) As for the TC, a mixture of ice and water in a styrofoam container or thermos will be fairly constant (but not 0.00°). You can also stick the TC into a chunk of Styrofoam to shield it.

 

Ice-water bath for calibrating to 0.0°C perfectly acceptable in most cases. Not to certified lab standard but acceptable. And the temp even with a 10 second polling time is fairly stable. For grins and giggles cut the delay down and watch the output after shielding the sensor and see what happens. I would accept anything within 0.1°C differential as great.

 

@SamR
I don't think the problem is accuracy. That's why I added that bit about not being exactly 0.00°C.

I think the sort of variation being seen is due likely to air currents. I saw similar changes with the companion digital chip. It's very sensitive. Just walking past it could be detected.

Also, the DS recommends a 10 nF noise filter. The Adafruit board includes that; not sure about the other board. I consider it pretty likely it does too.

 

My experience with them and I tried several was slow change. Blowing on it didn't work but pinching between thumb and finger did cause slow change. I did the DCS work for a still project where the outside hired PE hotshot said he could control the 130' tall multi tray fractional distillation column still within 0.001°C. He speced the hardware for me to buy and our intrument techs installed it and I did all the DCS programing and damned if he didn't actually do it. Of course, we are talking about industrial hardware and not Arduino modules.

 

Between post 64 and 65 did a post go missing? I thought I saw some temps posted and a few boards. Let the dogs out between rain showers and now I don't see it? The temps looked close to me but now I seem to have lost an entire post?

Ron

 

Between post 64 and 65 did a post go missing? I thought I saw some temps posted and a few boards. Let the dogs out between rain showers and now I don't see it? The temps looked close to me but now I seem to have lost an entire post?

Ron

There are duplicate threads. Maybe our mods will combine all the MAX 31855 comments into the new thread.

 

My experience with them and I tried several was slow change. Blowing on it didn't work but pinching between thumb and finger did cause slow change. I did the DCS work for a still project where the outside hired PE hotshot said he could control the 130' tall multi tray fractional distillation column still within 0.001°C. He speced the hardware for me to buy and our intrument techs installed it and I did all the DCS programing and damned if he didn't actually do it. Of course, we are talking about industrial hardware and not Arduino modules.

My experience with the MAX 31856 is quite different. Just walking past it from one room to another was detectable. My hot teenage breath caused a huge and quick change (it was Winter). That's why I built a Plaster of Paris + vermiculite artificial "Pork Roast" with a heating blanket to get steady readings. As already mentioned, I also added insulation to the IC to shield the reference junction from short term atmospheric breezes.

 

I haven't played with the MAX module. I was using the LM35 & TMP36. Not the module boards, just bare TO-92s. With a generic UNO. Had the exact same problem with one and the other worked fine. Never did find my notes or at least I thought I made a notebook entry about the problem I was having. I always suspected it was a sensor problem. He is still using double precision! in his code I noticed.

 

AD offers 3 different sensor boards work with Arduino if you need more precision, Sometimes thermister or sometimes even RTD.
learning why the features might work for someone and why some are going I2C, The overview of what is available is shown below.
Both conditioning and software have internals that work with hardware that make the last digit dependable is integrated plug and play.
Modifications for specific environment or analysis software can be made by accessing the serial port. Shown in video presentation below.
If this system should crash an LM35 could be a backup. Ol' analog will still work while new chip can be replaced cost $3
https://www.analog.com/media/en/technical-documentation/data-sheets/ADT7420.pdf
The overview here arduino/linduino code:
https://www.analog.com/en/design-ce...oards-kits/ev-tempsense-ardz.html#eb-overview
Guide for loading arduino code to the sensor board:
https://www.analog.com/media/en/technical-documentation/user-guides/EV-TEMPSENSE-ARDZ-UG-1656.pdf

The sensor presentation from the conference and expo, sorry I don't have the conference link :

 

There are duplicate threads. Maybe our mods will combine all the MAX 31855 comments into the new thread.

Thank You.

Ron

 

This thread continues at the URL below.
https://forum.allaboutcircuits.com/...lues-not-stable-max31855.171630/#post-1535861