A Thermometer With a Mechanical Transmission System That Will Exceed Your Expectations

A thermometer with a mechanical transmission system that will exceed your expectations

I recently noticed the thermometer at home, and it matches my traditional concept of what a thermometer should be. However, it seems that contemporary manufacturers often lack creativity in their designs. They typically attach an LED screen to a simple, square-shaped device, resulting in a dull appearance that doesn't harmonize well with the home decor. This led me to consider using the classic look of a traditional thermometer while incorporating mechanical structures to display the temperature. By employing synchronous belt gears to convey temperature changes, it could transform into a standout feature in the household.

Structure:

To begin with, selecting the right materials is crucial. I was initially undecided between acrylic and basswood panels, unsure which would be more appropriate. However, after examining the interior design of several homes, it became clear that wood finishes are generally preferred. As a result, I've decided that using layered basswood would be the more suitable option.

In line with a more contemporary style, the wooden panels are also easier to process, facilitating subsequent procedures. For temperature display, I plan to use a mechanism similar to that of a 3D printer: employing a stepper motor to drive a timing belt, which in turn moves the pointer across the dial. This approach ensures the stability of the pointer and the accuracy of temperature indication. I had also considered using a lead screw and slide table for the drive mechanism, but ultimately abandoned this idea due to the high cost associated with lead screws and slide tables.

The next phase is selecting the motors and drive components. The widely used 42 stepper motor, known for its excellent stability, is a popular choice in robots and 3D printers. However, its size makes it unsuitable for thermometers. After careful evaluation, I opted for the 28BYJ48 geared stepper motor.

This stepper motor is compact in size and operates at low current, which can be driven by the ULN2003 chip. It is also more affordable than the NEMA 17 stepper motor and comes with a reduction gear, ensuring adequate torque. The output shaft is a 5mm D-shaped shaft that is compatible with commonly available synchronous pulleys on the market. For the transmission system, standard components frequently used in 3D printers can be employed. I used a 16-tooth GT2 synchronous pulley as the driving wheel to drive the timing belt, while the driven wheel setup is quite simple, requiring only two bearings. This approach is both straightforward and cost-effective, eliminating the need to purchase idler pulleys. The tension of the timing belt determines the accuracy of the pointer's indication, so I added a tension spring to ensure the timing belt remains taut at all times.

There are several ways to make a pointer. I chose to use a paperclip to display the temperature; it can be securely fastened to the timing belt, ensuring it remains stable and doesn't shift.

Circuit:

For the microcontroller, I opted for the Arduino Uno.You could purchase from the unikeyic.

The Arduino Uno supports numerous open-source libraries and sensors, making it exceptionally easy and user-friendly for programming. Unlike other microcontrollers that require an understanding of various complex registers, the Arduino Uno can achieve many functionalities with simple commands. In terms of performance, the Atmega328 microcontroller embedded in the Arduino Uno offers sufficient resources, and its RISC architecture enhances its capabilities, making the Arduino Uno more than adequate for this project.

Once the microcontroller is chosen, selecting the other components becomes significantly simpler. For temperature measurement, I decided on the DHT11 temperature and humidity sensor, which can track both environmental temperature and humidity levels. Its single-wire data transmission method saves port resources, and thanks to Arduino's open-source platform, utilizing this sensor is extremely easy—one function call retrieves both temperature and humidity information. This makes it a perfect choice for constructing a thermometer.

To drive the stepper motor, I'm utilizing the ULN2003 high-power Darlington transistor array module. This module is easily accessible and affordable, making it a perfect match for the chosen stepper motor. The integrated 4-channel LED indicators clearly display each phase's operational status.

We would like to again express our gratitude to Arduino for providing the open-source environment and to Unikeyic for their hardware support. Due to the efforts of many experts, the function library for this driver module has already been developed for us, so we only need to utilize it. Below is the carefully crafted circuit diagram:

With the structural design and component selection finished, the next step is to draft the blueprints for the wooden panels. After a short but focused effort, the blueprints are completed and sent to the manufacturer for cutting. A few days later, the cut wooden panels are delivered.

The next step is installation. Gently position each component in its assigned spot and ensure that all wiring is correctly connected.

Program：

Connect the computer, upload the code to the Arduino Uno, open the serial monitor, and observe the temperature values displayed on the screen.

Adjust the locations of the paperclip pointer and the tension spring. Once these modifications are made, you'll have a thermometer that perfectly integrates technological innovation with artistic design.