Many of the clocks we feature here on Hackaday are entirely built from scratch, or perhaps reuse an unusual display type. But sometimes, an old clock is just perfect as it is, and only needs a bit of an upgrade to help it fit into the modern world. One such example is the lovely 1960s Copal flip clock (in German, Google Translate link) that [Wolfgang Jung] has been working with — he managed to bring it squarely into the 21st century without changing its appearance one bit.
Like most flip clocks from the 60s and 70s, the Copal clock uses a small synchronous AC motor to advance the digits. Because this motor runs in step with the mains frequency, it also acts as the clock’s timing reference. However the original motor had died, and a direct replacement was impossible to find. So [Wolfgang] decided to replace it with a modern stepper motor. He designed a small PCB that fit the original housing, on which he placed a Trinamic TMC2225 stepper motor driver, a Wemos D1 Mini and a small 5 V power supply.
Thanks to its WiFi connection, the D1 can find out the correct time by contacting a Network Time Protocol (NTP) server. Displaying that time would be tricky with the original hardware though, because there is no indication of which numbers are displayed at any time. [Wolfgang] cleverly solved this problem by placing an IR proximity sensor near the lowest digit, allowing the D1 to count the number of digits that have flipped over and thereby deduce the current state of the display.
There’s plenty of fun to be had with classic flip clocks like this, and with a bit of hacking any old split-flap display should be usable for your own clock project. If none are available at your local thrift store or yard sales, you can always roll your own.
Technically, the clock works just like a regular flip clock, except that only the upper half of the split-flap is used to display the digits, while the lower half is showing the cards’ backsides. Other than that, the mechanics are the same: a set of hinges holding the cards are arranged on a rotor that’s moved by a stepper motor until the correct digit is shown (STLs available on Thingiverse). Aces low, Jokers are zeroes, and the queen strikes at noon.
At the center of it is an ESP32 that controls each digit’s motor driver, and retrieves the time via WiFi, keeping the general component count conveniently low. Of course, one option is to arrange the cards in their order to keep rotations at a minimum, but let’s be real, the flapping sound is half the fun here. So instead, [Shinsaku Hiura] arranged the cards randomly and mapped it in the code accordingly. You can see it all in action, along with some additional design information, in the video after the break.
LED and LCD displays are a technological marvel. They’ve brought the price of televisions and monitors down to unheard-of levels since the days of CRTs, but this upside arguably comes with an aesthetic cost. When everything is covered in bland computer screens, the world tends to look a lot more monotonous. Not so several decades ago when there were many sharply contrasting ways of displaying information. One example of this different time comes to us by way of this split-flap display that [Erich] has been recreating.
Split-flap displays work by printing letters or numbers on a series of flaps that are attached to a spindle with a stepper motor. Each step of the motor turns the display by one character. They can be noisy and do require a large amount of maintenance compared to modern displays, but have some advantages as well. [Erich]’s version is built out of new acrylic and MDF, and uses an Arduino as the control board. A 3D printer and CNC machine keep the tolerances tight enough for the display to work smoothly and also enable him to expand the display as needed since each character display is fairly modular.
The venerable flip clock has become an outsized part of timekeeping culture that belies the simplicity of its mechanism. People collect and restore the electromechanical timepieces with devotion, and even seek to build new kinds of clocks based on split-flap displays. Designs differ, but they all have something in common in their use of gravity to open the leaves and display their numbers.
But what if you turned the flip clock on its head? That’s pretty much what [Shinsaku Hiura] accomplished with a flip clock that stands up the digits rather than flipping them down. The clock consists of three 3D-printed drums that are mounted on a common axle and linked together with gears and a Geneva drive. Each numeral is attached to a drum through a clever cam that makes sure it stands upright when it rotates to the top of the drum, and flops down cleanly as the drum advances. The video below makes the mechanism’s operation clear.
The build instructions helpfully note that “This clock is relatively difficult to make,” and given the extensive troubleshooting instructions offered, we can see how that would be so. It’s not the first time we’ve seen a mechanically challenging design from [Shinsaku Hiura]; this recent one-servo seven-segment display comes to mind.
With little more than four economical stepper motors, a Raspberry Pi Zero, and a 3D printer, [Thomas Barlow] made himself an awfully slick Smart Flip Clock that can display not only the time, but also weather data as well. This is done by adding a few extra graphics to some of the split-flaps, so numbers can also be used to indicate temperature and weather conditions succinctly. Displaying the time has to do without a colon (so 5:18 displays as 518), but being able to show temperature and weather conditions more than makes up for it.
According to the project’s GitHub repository, it looks as though each split-flap has thirteen unique positions. The first ten are for numerals 0 through 9, and the rest are either blank, or used to make up a few different weather icons with different combinations. A Python script runs on the Raspberry Pi and retrieves weather data from OpenWeather, and the GPIO header drives the display via four geared stepper motors and driver boards. The rest of the hardware is 3D printed, and [Thomas] helpfully provides CAD models in STEP format alongside the STL files.
It hardly seems possible, but engineer collective and split-flap display purveyors [Oat Foundry] were able to build a working implementation of Tetris on a 10 x 40 split-flap display in the span of a single day. Check it out in the video after the break.
This project is a bit understaffed in the details department, but we do know that [Oat Foundry] started with [Timur Bakibayev]’s open-source implementation of Tetris in Python and modified the draw function to work on a split-flap display. As you may have guessed, the biggest obstacle is the refresh rate and how it affects playability — particularly during those tense moments when a player rotates a piece before dropping it. Split-flaps flip quickly from on to off, but flipping back to on requires a full trip around through all the other characters.
We think this is nice work for a one-day build. Should they go further, we’d like to see the same things implemented as [Oat Foundry] does: a high score tracker and a preview of the next piece.
This fantastic-looking ‘bot stands on the shoulders of [Scott Bezak]’s trailblazing method for easy DIY split-flap displays. Push the rather inviting-looking button on the top, and the flaps start flipping around to find your fortune. Once the fates have aligned, a thermal printer on the front spits out an image of your card along with an interpretation.
It’s obvious that [i_mozy] put quite a lot of effort into this slick machine, and we think the stickers look especially great. All the details of physical tarot card readings are accounted for, including a random number to decide the card’s position, and LEDs to represent the card’s element. Suspend your disbelief and check out the demo/promo video after the break.