In my previous post about reading thermistors with a Wemos D1 Mini, I observed resulting output seemed a bit high at lower temperatures, while readings were lower compared to other sensors at higher temperatures. As I explained, that problem was in part due to variable input voltage. Even after fixing that issue, there were a […]
Category: Thermometers
Getting accurate NTC thermistor readings with a Wemos D1 Mini
A thermistor is a very common type of thermometer. They are cheap and readily available in many forms. At first glance, thermistors are very simple devices. It is basically a resistor that changes its resistance with temperature. Very popular are 10K NTC thermistors. Negative Temperature Coefficient (NTC) means that resistance drops when temperature rises. 10K […]
Active versus passive ventilation under high radiation
It’s June. An ideal month in the Northern Hemisphere to observe the effectiveness of radiation shields under high solar radiation. Two of my main sensor setups are a passively ventilated Barani MeteoShield Pro with an SHT35 sensor and the actively ventilated Apogee TS-100 with PT100 sensor. In theory, there should be situations where the Barani […]
Temperature sensor responsiveness (part 2)
In February I wrote a post about the responsiveness of the temperature sensors I am using. One caveat I noted then, was that I was comparing SHT35 sensors with PT100 sensors while the latter were actively ventilated and the first were not. In the mean time I made a few changes to my setup. Most […]
Temperature sensor responsiveness
The passing of a sharp weather front, accompanied by a sudden increase or decrease in temperature, is a good occasion to analyze temperature sensor behavior. Especially apparent becomes the responsiveness of different sensors. February 4th 2022 didn’t see any spectacular weather, but during the afternoon a cold front passed over which caused a very abrupt […]
PT100 measurements: MAX31865 vs 4-20 mA
Since very recently I have two identical PT100 sensors set up inside the same fan-aspirated shield. The first sensor is read using the Adafruit MAX31865 breakout board, while the second is linked to a 4-20 mA current loop transmitter. In both cases, a Wemos D1 Mini microcontroller is used to process the signal. For the […]
Using a 4-20 mA PT100 transmitter
In this post, I explained how I used an Adafruit MAX31865 clone in order to read a PT100 temperature sensor. Since then, I’ve tested an original Adafruit version as well. Accuracy from this board is a lot better. While I had to add a calibration offset of somewhere between 0.8 and 1.5 degrees to configurations using the […]
Looking for stable PT100 readings
In a previous post I explained how I used the MAX31865 with a Wemos D1 Mini to read a PT100 sensor. This worked, but initial readings were erratic. Readings were also off by about 1 degree C. Almost two weeks later, I have tested 3 different PT100 sensors. I now have an Arduino sketch running […]
Reading a PT100 sensor with a Wemos D1 Mini
In my never ending quest for better temperature readings – or other ways of doing so, at least – I’ve begun trying other sensors than the SHT35. One of them is the PT100. It’s supposed to be very accurate. It it used in many different situations, from laboratory settings to industry. It’s also used in […]
Apogee TS-100 first impressions
I was losing the last light and had to get a flash light while connecting the last wires Tuesday evening (August 17th), but I have the TS-100 up and running. Without battery backup for now. I will fix that later. Adding this new shield to my setup has triggered a whole series of new tests […]