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The traditional analog clock with its two or three hands has existed in its current form for hundreds of years. Instructables user Gammawave had the idea to expand on this concept by replacing the physical hands with glowing ones that don't even physically exist. Their design, called the Analumi clock, revolves around taking a motor attached to a photo-sensitive disc, which rotates above a single arm of ultraviolet LEDs. When the lights are powered on, the cast rays hit a sheet of photo-luminescent material above it, thus creating a glow at the desired angle. This entire series of events are also repeated for the minute hand's position.

In order to control the central motor and LEDs, Gammawave went with a Micro:bit V2 board due to its simple programming language and built-in speaker module. It was then connected to a breakout board that houses additional circuitry for driving motors, which was then wired to a simple 5V stepper motor driver. The Micro:bit is able to track the current time thanks to an Adafruit real-time clock module, while the ultraviolet light is emitted by eight UVA LEDs.

Upon powering up the clock, the motor first performs a simple homing sequence, which rotates the physical armature to a fixed point using a magnet and Hall-effect sensor. Once this starting point is known, the current hour and minute are read from the RTC and converted into two separate angles, thus telling the stepper motor how far to rotate. After reaching either of the two angles, the line of LEDs is switched on for a set amount of time before waiting a minute to repeat the same series of steps.

The large photo-luminescent disc was made by taking a CD and cutting a pair of mounting holes for the stepper motor to interface with. In doing so, the motor can spin the surface over the fixed line of LEDs to create new patterns rather than having to move the LEDs. Behind this is a large box that keeps all of the electronics and power supply hidden away from the viewer, as well as housing a power switch. Last of all, a clear acrylic sheet was added over everything for added protection.

Setting the time is done by using the pair of buttons on the rear of the clock to enter the current hour and minute along with either the 12-hour or 24-hour time format. From here, the stepper motor runs through a homing sequence and begins to draw the hour and minute hands with its LED bar. For more information about the Analumi clock, you can read Gammawave's write-up here on Instructables.

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