This cool DIY thermometer uses your phone’s RFID field to power itself

What kind of stuff do you think you can power with an RFID field? It turns out that it can muster just enough power to charge a small digital thermometer long enough for it to take a reading. Someone created a board that does just that, and if you like it, you can make or purchase your own.

This clever device uses RFID fields to power a thermometer

As spotted by Hackaday, this intriguing invention is the idea of Bjorn on Hackaday.io. It’s a little ATTiny1626 board that sits on your keychain with an RF430CL330H dynamic RFID IC and a 13.56 MHz antenna. It doesn’t have an active supply of power, but the magic happens when a device that uses RFID (like your phone) is nearby:

When approached by a RFID reader some of the energy from the magnetic field is siphoned and stored in a capacitor to power the microcontroller for just long enough to read the thermometer and write the result to the dynamic RFID tag. The tag is then read by the reader (most likely a phone) and the temperature with 0.1 °C accuracy (in range -20 °C – 50 °C, total range -55 °C – 150 °C) is then displayed as a text based RFID tag.

If you’re interested, you can check out the above video showing the board at work. Bjorn demonstrates bringing the phone close to the board and getting a reading on-screen, with a more heavy-duty thermometer to the side to show the actual temperature as proof. You can check out all the open-source hardware and software on the project’s GitHub, and if you’d rather have someone else grab it for you, you can buy one for $35 on Tindie. That gets me thinking; I wonder if you can power it using a Flipper Zero?