Transmission system that will exceed your expectations
I happened to notice the thermometer at home. This kind of thermometer aligns with my traditional understanding of what a thermometer should look like. However, modern manufacturers seem to lack creativity in their designs. They simply slap an LED screen onto a basic, square-shaped device, which looks quite dull and doesn't blend well with the home environment. Therefore, I thought about utilizing the classic appearance of a traditional thermometer, integrating some mechanical structures to display the temperature. By using synchronous belt gears to convey temperature changes, it could become a highlight within 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 step involves choosing the motors and drive components. The commonly found 42 stepper motor is often used in robots and 3D printers due to its outstanding stability. However, its large size makes it impractical for use in thermometers. After thorough consideration, I decided to go with 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 various methods for creating a pointer. I used a paperclip to indicate the temperature; the paperclip can be firmly attached to the timing belt, making it stable and resistant to movement.
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.
After selecting the microcontroller, choosing the remaining components becomes much easier. For measuring temperature, I opted for the DHT11 temperature and humidity sensor, which can monitor both environmental temperature and humidity. Its single-wire data transmission method conserves port resources, and with Arduino's open-source platform, using this sensor is incredibly straightforward—just a single function call retrieves temperature and humidity data. This makes it an ideal choice for building 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. Thanks to the contributions of numerous experts, the function library for this driver module has already been written for us, and we merely need to call upon it. Here is the meticulously designed 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. Next comes the installation. Carefully place each component in its designated position and properly connect the wiring. Program： Connect the computer, upload the code to the Arduino Uno, open the serial monitor, and observe the temperature values displayed on the screen. Modify the positions of the paperclip pointer and the tension spring. Once these adjustments are completed, you will have a thermometer that seamlessly blends technological innovation with artistic design. TAG：Stepper motor;Temperature and humidity sensor;Transistor
