WiFi Temperature Sensor

WiFi Temperature Sensor

To control my heating via Home Assistant, I needed some temperature sensors. These should be powered by mains voltage and not by batteries, so they can reliably deliver temperature readings

WARNING

This project is only for people who know what they are doing. It involves the use of 220V mains voltage, which can be fatal if touched. I assume no liability for damages of any kind that may arise from replication

Requirements

Required Knowledge

• Soldering experience
• ESP Home
• MQTT

Parts

• ESP32-C3 Supermini
• Dallas DS18B20 Temperature Sensor
• 5V Plug-in Power Supply

The links point to AliExpress items that I used

Printing

The number on the lid can be easily changed by coloring the segments with the paint bucket and edge detection feature

Make sure the print bed is clean, otherwise the housing will fall over. If you like, you can use some “mouse ears” (brim)

Electronics

Carefully pry open the plug-in power supply on the plug side with a knife or small screwdriver and pull it apart

The following pictures show the assembly of the electronics. Due to the simple circuit, I did not include a circuit diagram

Clicking on the photos makes them larger

Solder the Dallas Sensor onto a 20x10mm PCB. A 4k7 SMD resistor goes between Vcc and DQ	Solder 5V and GND cables to the plug-in power supply	Connect ESP32-C3 and sensor as shown (GND, 3.3V and Pin 4 to DQ)	Connect 5V from the power supply to ESP32-C3 5V, connect GND to the sensor board GND

Final Assembly

First, unplug the power supply and snap it into the printed housing

Arrange the electronics	Insert the power supply so that it has firm contact with the plug	Insert the ESP32-C3 board with the USB port first
Insert it so that the USB port sits in the designated hole	Carefully push the ESP32 board up from the back with a screwdriver until it clicks into place. Slide the sensor board into the designated guide. Pay attention to the cables here!	Insert the front panel, the temperature sensor should be at the bottom

I have attached my ESPHome code, it works with MQTT. Of course, other solutions are also possible. The housing can also accommodate a combined temperature/humidity sensor

Programming can be done via the USB port without the device being plugged in

Please remember to work cleanly and double-check everything before plugging the device into the socket. And as I said: It's not my fault :-)

Have fun tinkering and always a warm home