Ever found yourself disappointed by a gadget that just didn’t meet your expectations? That’s exactly what happened to one DIY electronics enthusiast who ordered a digital watch kit online, only to find it wasn’t quite what he hoped for. But instead of shrugging it off, he decided to do something about it. Enter his custom digital watch with minimal parts and a 3D-printed case.
But this isn’t just any DIY project. It’s a super-efficient, minimalist watch that lasts many months on a single coin cell battery, thanks to some clever design choices and ultra-low power consumption.
His watch uses an ATmega328P microcontroller, the same microcontroller found in the first Arduino UNO variant. The watch features a 7-segment display to display the time and an RTC(Real Time Clock) IC to keep accurate track of time.
Also read: Raspberry Pi Pico with DS1302 RTC (MicroPython Code)
A pushbutton protruding from the watch case helps to wake up the microcontroller and display the time. The maker used SolidWorks 3D CAD design software to design the watch case. His final design of the watch features a 24 mm strap size.
Although the watch does not have fancy hardware such as an accelerometer or a temperature sensor, where it shines is its very low power consumption. In sleep mode when the display is OFF, the watch has been demonstrated to consume only 15 micro Amps of current.
Upon pressing the push-button switch, an interrupt is triggered and the device wakes up to display the time. The watch consumes around 11mA current while the display is ON. The display turns OFF after a few seconds and the watch goes back to sleep mode.
The maker claims the watch can last more than a year when running on a single CR2032 coin cell battery. He also shows calculations backing up his claim. In a scenario where the watch is kept only in sleep mode, the battery can last 555 days, while it will last 18 hours if the display is kept running all the time.
If the watch is programmed to keep the display ON for 10 seconds upon each button press, and if a user presses the button 10 times a day to view the time, the battery will last for more than a year (1 year 190 days as calculated). Isn’t that amazing?
The maker plans to sell a fully programmed and assembled PCB without the case. You can join his mailing list by visiting his website where he also sells watch kits, parts, and 3D-printed cases.
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