Have you ever wondered what it would be like if an old rotary phone combined with a modern smartphone? Recently, engineer Justine Haupt from the Brookhaven National Lab in the USA transformed an old rotary phone into a portable mobile phone using a 3D-printed case and a microcontroller.
Initially, Justine wanted to create a unique phone for herself, so she laid everything out flat and created a theoretical prototype using an Arduino Micro controller board.
Additionally, she actually filed down and cut some parts of the rotary structure to make it compact enough for a phone.
Then she assembled all the components into the pre-printed case, but it turned out that this step was a bit hasty as she couldn’t continue modifying the circuit without damaging the case.
Thus, the second version was born. Now it can indeed be used as a mobile phone, but it still has various minor issues. The standby time is only two hours, and it uses Adafruit FONA 2G, which is a fatal mistake as she did not realize that 2G networks are gradually shutting down during the design phase. However, she is just a step away from real success.
After a series of designs and modifications, the final version, v3, was introduced.
v2 used the ATmega2560 microcontroller, while v3 uses the low-power version ATmega2560V. It is programmed in the Arduino IDE just like using Arduino Mega2560. The battery’s standby time has also increased to 24 hours, and the back of the phone features a 2.1-inch flexible electronic paper screen to view missed calls and messages. An LED on the side indicates signal strength and battery level. Since there is no menu, she set up frequently used contacts on hotkeys, allowing her to call family and friends with one click. After all, using the rotary dial for every call would be more of a hassle than fun.
After a series of adjustments and tests, it is now a real mobile phone, equipped with one-click calling, a sliding switch, and notifications for calls and messages. At the end of the article, relevant schematics and KICAD files will be attached. If you are interested, feel free to try modifying it at home.
Schematic:
USB bridge :
KICAD:
For more design details and related files, click to read the original text.
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