June 16th, 2022—
Nearly everyone is familiar with the mercury thermometer and how it uses the expansion of the element to display ambient temperatures. But in Instructables member TurboSnail’s latest project, they attempted to turn this concept on its head by making a thermometer that uses the iconic Freddie Mercury to show the temperature without the need for the toxic liquid metal.
The plan for this project involved a quite simple circuit. An Arduino Nano Every would read the current temperature and humidity levels using an Adafruit AHT20 sensor module and map them to Freddie’s arms and a set of LEDs, respectively. To help reduce current consumption in this battery-powered display, the servo motor only receives power when a transistor is switched on by the microcontroller for brief periods of time.
After assembling the circuit and getting the code to work, TurboSnail then moved their attention to designing a cool-looking PCB that features the dial face complete with temperatures and sayings, a smaller humidity scale at the bottom, and a large silkscreen figure of Freddie along with pads on the back for soldering the larger components. Freddie’s arm was 3D-printed and attached to the micro servo motor while the Nano Every was replaced by a lower-power DIY Uno board. Last of all, the PCB was fitted inside of a custom wooden enclosure and switched on.
To see more about the Mercury Thermometer, you can read TurboSnail’s write-up here on Instructables or watch the demo video below!