This Unique Clock Displays Digits as Magnetic Fields

We’re centuries past the point when clocks were purely practical devices. In a time when most of us check the time on our smartphones, smartwatches, or computers, standalone clocks must be decorative as well as practical — with many people prioritizing aesthetics over utility. An example of that, Moritz v. Sivers' Magnet Viewing Clock displays digits as magnetic fields.

Magnetic fields are invisible to the naked human eye, but their effects are not. You can, of course, see a pair of magnets come together or move apart as they repel or attract each other. You can also see magnetic fields in substances like iron filings. Magnetic viewing film works in the same way, with ferromagnetic flakes suspended in oil sandwiched between two sheets of transparent plastic film. In the absence of strong magnetic fields, those flakes remain scattered throughout the oil in a mostly uniform manner. But when exposed to strong magnetic fields, the flakes will clump together and orient themselves to the field, which makes them visible.

In this case, Sivers cut out numbers from magnetic foil. When they position magnetic viewing film over those numbers, they become visible. To construct the clock, Mosivers just needed to control which numbers are visible at any given time. They achieved that by attaching the magnetic foil numbers to four wheels behind the magnetic film. As the wheels spin, they move the magnetic numbers across the magnetic viewing film. The four wheels represent the four digits of the clock and four boxes drawn onto the magnetic viewing film indicate which number is “active.”

Four small pancake stepper motors spin the four number wheels. An Arduino Uno with a CNC Shield and stepper drivers control the positions of those motors. The Arduino tracks the current time using a DS3231 RTC (Real Time Clock) module. Sivers plans to add hall effect sensors to home the number wheels, but for now the user must home them manually. The clock’s enclosure and number wheels were 3D-printed, and Sivers made the magnetic numbers using a vinyl craft cutting machine.

Sivers says that they aren’t completely happy with the result, as the contrast is low and the numbers are hard to see. But it looks great in the photos and one can improve the contrast by using stronger magnetic numbers or moving those numbers closer to the magnetic viewing film.