Antonki Thermometer/Hygrometer is sold at $8 for two. It claims a temperature range of -50 to 70°C (-58 to 158°F) with accuracy +/-1°C and relative humidity range 10% to 99% with accuracy of +/-5%. It is good value if it is indeed accurate.
We use SHT31 and HTU21 breakout boards with Arduino Nano and an OLED display module (0.96" OLED 128x64). Arduino 3.3V output is used to power the sensors and the display. Very quickly, we pull together the code needed to read from the sensors and display the data on the OLED module. It shows the power of Arduino. We update the reading every 3s.
For temperature, we also have the analog thermometer, thermocouple, and PRT measured by multimeter, and Fluke non-contact IR thermometer. The temperatures are measured at four settings, ambient (22°C), refrigerator (3°C), freezer (-18°C), and heater (50°C).
Here are the results. The readings deviate greater at the colder temperatures.
| Sensor | Freezer | Refrigerator | Ambient | Heater |
|---|---|---|---|---|
| Antonki | -15.9 | 5.5 | 22.2 | 46.5 |
| HTU21 | -17.3 | 5.8 | 22.6 | 46.5 |
| SHT31 | -17.1 | 5.5 | 22.4 | 46.6 |
| TC | -21.0 | 3.0 | 18.0 | 46.0 |
| PRT | -17.4 | 6.0 | 22.8 | 48.5 |
| Thermometer | -19.0 | 3.0 | 22.0 | 51.0 |
| Fluke | -16.4 | 4.2 | 22.5 | 46.5 |
We compare a few humidity readings. Since HTU21 and SHT 31 disagree by 10%, it is hard to assess the accuracy.
| Sensor | Reading 1 (% RH) | Reading 2 (% RH) | Reading 3 (% RH) |
|---|---|---|---|
| Antonki | 55.0 | 31.0 | 71.0 |
| HTU21 | 46.5 | 26.2 | 59.0 |
| SHT31 | 56.4 | 34.6 | 69.4 |
It should also be noted that the response time of Antonki is slow; it takes time to stabilize the readings, especially the humidity.
In conclusion, Antonki Thermometer/Hygrometer is usable at normal room temperature range.
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