robi@Discord
Calibration of 53 pieces of DS18B20 Dallas sensors simultaneously. 32 of them waterproof model, so doing 2-point calibration for these:
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Conclusion
- DS18B20 solderable PCB (TO-92 packaging) are worse quality, and since they are not waterproof, they can only be calibrated to a reference, and then the measured offset can be applied (possible in ESPHome and Tasmota, also in HA with templating). Try calibration close to the temperature where it will be used intentionally, as it’s likely that the linear offset is still unprecise.
- DS18B20 waterproof version are better, and can be calibrated using 2 points. Since we all learned in school that water boils at 100C, and water and ice present in the same time is at 0C (at sea level) it’s possible to do actual measurements of what the sensor sees in these practical conditions. ESPHome has
calibrate_linearandcalibrate_polynomialfunctions which allow for much more precise compensation than a simple offset.- SHTC3 is simply great. 0.1 or 0.2 degrees difference is acceptable.It’s not waterproof but it still can be tweaked with a linear offset, given that there’s a good reference to be compared with.
One could select a reference sensor from the pack of multiple DS18B20 waterproof sensors. From my 32 pieces I found one which was measuring 99,9C at water boiling, and -0,1 at iced water so I’ll set that aside and label it as reference sensor for the future.
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