[Jens] wanted a subscriber counter for his YouTube channel. He could have gone with a simple OLED, LCD, or LED display, but he wanted something more tactile and interesting. So he built a mechanical 7-segment display instead!
Currently, [Jens]’s channel is in the four-digit subscriber range, so he planned to build a four-digit display. He started by searching for existing projects in this space, and came across the designs of [shiura] on Thingiverse. [shiura] had a 3D printed cam-driven 7-segment digit that runs on a single servo motor. Once armed with four of the digits, he hooked them up to a Pi Pico W to drive them all with four servo outputs. The Pico W is responsible for querying the channel subscriber count online, and updating the display in turn.
It’s a neat build, and [Jens] learned some things along the way—like how Super Lube seemed to ruin filament for him. Ultimately, the build came good, and it looks great. We’ve seen some other mechanical 7-segment builds before, too!
Well written article, thanks for posting! :)
I wonder if it would be possible to make a simple pulse relay type of flip dot display.
If you have a magnet and a coil with an iron core, pulsing current in one way would make the magnet turn one way and latch onto the iron core, because the iron retains the magnetic field in that orientation. Pulsing current the other way would flip the magnet around again. This could be accomplished by charging and discharging a capacitor through the coil – no current flows in the steady state, only when the display is switching states. When the driving signal goes up, the capacitor charges and causes a pulse of current one way – when the driving signal goes down the capacitor discharges and the pulse of current goes in the other direction.
The magnet could be embedded in a tube with one side painted yellow and the other black, so the magnet makes it rotate black or yellow side front.