Split flap displays! They’re mechanical, clickety-clackity, and largely commercially irrelevant in our screen-obsessed age. That doesn’t mean you can’t have a ball making one of your own, though! [Morgan Manly] did just that, with tidy results.
An ESP32 C3 SuperMini serves as the boss of the operation, running the whole display. The display is designed to be modular, so you can daisy chain multiple characters together to spell longer words. Each module has 37 characters, so it can display the alphabet, numerals 0 to 9, and a blank. Each module contains a 28BYJ-48 stepper motor for controlling the flaps, and a ULN2003 driver board to run it and a PCF8575 IO expander to handle communciation. An A3144 hall effect sensor is also used for positional feedback to ensure the display always shows the right character. The flap mechanism itself is relatively straightforward—a drum with all 37 flaps is until the correct character is reached, with the blank flaps hosting a magnet to trigger the aforementioned hall effect sensor. The flaps themselves are 3D-printed, with filament changes used to color the characters against the background.
If you’ve ever dreamed of building a flap-display clock or ticker, you needn’t dream of finding the perfect vintage example. You can just build your own! The added bonus is that you can make it as big or as small as you like. We’ve seen some interesting variations on the split flap concept recently, too. If you’re cooking up your own kooky electromechanical displays, don’t hesitate to let us know!
