This is my attempt for a cheap temperature sensor powered by mains. I use some of these to control the heating in my house. The electronic is easy, it’s build with an ESP32-C3 supermini, an USB plug-in charger and a Dallas DS18B20 sensor. The real challenge for me was the case. I wanted something compact and nice looking which does not affect the measured temperature too much. After a lot of experiments I came up with this 3D printed case.
The case let you still access the buttons and the USB connector of the ESP, can be easily assembled without glue or screws and is also easily printable.
If case you are interested in the details, you can see and download all necessary information (including the code) from my project page on MakerWorld. This is free for private use.
Looks interesting. More than a decade ago I had a similar idea, but never actually got around to implementing it.
A few years ago I started buying cheap BT temp + humidity sensors. I like having the screen and find that I like the Govee H5075 best. I have some of the Mijia ones. They are smaller and can be converted to Zigbee, which didn’t seem to make them much better.
Depending on the cost of electricity in your area, the batteries might be cheaper (since they last a long time).
Yes, you are right, I also have some Zigbee temperature sensors with battery, some with screen some without. But I wanted a few main powered sensors just for peace of mind.
I bought the stuff on AliExpress, 1,89 € the ESP Supermini, 5 of the USB plug power supplies for under 4 € and a pack of 10 of the Dallas sensors for around 2 €. So this stuff is really cheap. None of the battery powered sensors has been available for that price.
And, last but not least, it has been some fun to develop this thing which could be also the basis for other devices.
I know. Used few as well until failed. There’s a difference between charger and charger.
Original Samsung one port 2A charger weights more than “100W 5-port Aliexpress fast charger”
Yes, there is some heat inside the case. This was the reason why I changed the design of the case more than once. But with the actual design and an interval of 1 min or more the heat is quite low. The sensor is at the bottom so the heat from the ESP (which is more than from the power supply) goes up and has a lower effect on the sensor.
All in all I was able to get pretty accurate readings in the temperature range of 16 to 22 degrees celsius by adding a simple offset to the measured temperature (may be the window is bigger, but this is what I tested). This is good enough for heating control. The device is not mentioned for measuring outside temperature or similar things which needs a big temperature window.
Did you consider to put the boards vertically so the case would be less sticking out but of course higher.
Like that, it could have less influence on the temperature maybe.
