Accurate Split-Flap Display Can Be 3D Printed

Split-flap displays are a great, low-power way to display text to a wide audience. Compared to other display technologies like LCDs they only use energy when the characters change, but have fallen out of favor partially because of their greater mechanical complexity and also because LCD and LED technology has become so inexpensive. They still retain a loyal following though, and [Jason] is demonstrating his version which boasts high accuracy and can be 3D printed.

To get good results, one of the keys is getting the motor positioning just right. The motor sits in the center and spins the flaps around, so stopping at exactly the right point to display a certain character is critical. [Jason]’s system uses a 28BYJ stepper motor with a magnetic encoder to ensure that the correct flap is displayed. The flaps themselves are completely 3D printed, using a method which allows for two colors to be printed even if the printer is only designed for a single color. Once printed, the flaps are installed on the wheel which is the outer ring of a planetary gear set with the stepper motor sitting in the middle.

Each character in the display is housed in a printed enclosure, and for [Jason]’s project he only needs five characters, so to control the entire setup he’s using a Raspberry Pi Pico. For more characters he suggests that it is still possible to use a smaller microcontroller like the Pico but a multiplexer may be needed. Of course, displays like this are not limited to characters alone. Take a look at this display which has custom flaps to display the current weather conditions as well.

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Dynamic RAM From First Principles

Before the past year, many of us took computer memory for granted. It was one of the lower-cost parts of a PC build and was usually available in whatever quantity one desired. As its cost has skyrocketed, a lot of PC builders and other users of computers in general are taking a deeper look at memory, how much is really needed, and what its functions truly are. [Igor] is working on a drum sequencer project which needs a small amount of memory, and has built this dynamic RAM from discrete components.

The first video goes into the construction of the memory array and how its addressed. It’s only eight bytes total, and using fairly large electrolytic capacitors to store data means that a gigabyte of this memory would take up well over a thousand acres, but it’s still enough memory for [Igor]’s needs. In addition to the capacitor, each bit uses a pair of diodes to determine if a read or write is occuring, and a set of transistors on the read and write busses to perform those actions. Worth noting here is that dynamic RAM like this needs to be refreshed because the capacitors lose charge over time, but these large capacitors can hold charge sometimes overnight, as [Igor] has confirmed experimentally.

There’s a followup video to the construction of these modules as well, where [Igor] demonstrates a number of ways this module can be used, from controlling LED arrays, 7-segment displays, and then installs it into his drum machine. With 64 bits available it’s capable of creating up to eight beats with eight samples available per beat. Although there are complete machines available for all of this, we appreciate his goal of not buying any pre-manufactured hardware and instead constructing it all from the ground up. There are analog drum machine options available in this same style as well.

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Building A Panel Mount OLED Display

There are a million and one cheap OLED display modules out there. The only problem is, they’re all assembled on bare PCBs with slight differences, and that frustrates efforts to mount them in a clean and tidy manner. [Galopago] decided to build a small OLED module that solved this frustrating problem.

The idea to pursue this came from off-the-shelf panel displays commonly used for power supply builds and other such equipment. These come in relatively standard sizes and are designed from the outset to slot neatly into a panel with a bezel that covers any ugly edges or awkward gaps.

The build began with a 48 x 29 mm enclosure grabbed from an off-the-shelf power panel meter. There are two PCBs—one holding the regulator and other equipment to run the display, the other carrying a set of screw terminals that make it easy to wire up the display to a piece of equipment. The SSD1306-compatible OLED screen itself connects to the first board with a flat flex cable, as is the norm.

If you find yourself often wanting to pop a small display into a piece of custom test equipment, this might be relevant to your interests. Files are on GitHub for the curious.

We’ve featured some other fun OLED hacks over the years, like this interesting effort to whip up displays from scratch in a home lab. If you’ve got nifty usability hacks of your own in the works, don’t hesitate to let us know.

Deltarune’s Tenna Brought To Life

For those who have never played the hit video games Undertale and Deltarune, the games are partially known for their interesting characters, many of which have eerie, surreal, and expressive designs. One of the more memorable characters from Deltarune is Tenna, a game show host of sorts whose distinguishing feature is an old television as a head, as well as a colorful suit. As a result he’s been the subject of a number of recreations by various cosplayers and makers like [BigRig Creates].

This version of the character was actually inspired by a previous build by [BunnyBii] which used an iPad as the interactive screen/face. Inside the television, though, the actual human found this to be front heavy and limiting in the ways that it could be used interactively, especially since the only way to see the outside world in this version was with a small endoscope and screen. [BigRig Creates]’s version builds on this idea but swaps out the iPad for a Raspberry Pi, allowing for much more customization, and uses a pair of Xreal glasses instead of a screen for the view of the outside world from in the television.

To get the whole costume together, the head is 3D printed with all of the electronics inside, and a game controller integrated into a handheld microphone controls the animations shown on the screen. A vibrant, custom-tailored suit with white gloves rounds out the ensemble, along with a pair of 3D-printed shoe covers since actual yellow shoes were a bit pricy. There were some interesting problems to solve along the way, specifically with regards to power management for all the electronics, but in the end it all seems to have come together quite well. [BigRig Creates] is no stranger to builds with unusual displays, though; one of our favorites was the world’s largest Nintendo 3DS.

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A Camera Viewfinder Makes A Great TV

When we think of CRT camera viewfinders, most of us probably imagine the tiny CRTs you’d find in a 1980s camcorder. They’re super cute and a load of fun to play with, but they’re very much a consumer device. Professional cameras of the type you’d find in a studio had their own viewfinders, which were a lot closer to a small TV. They’re about as high quality as it gets for a monochrome CRT, and [Evan Monsma] has done the conversion to a general-purpose monitor.

On one side, this is a very straightforward hack, simply a case of tracing wires to identify the power and video pins. Given a tool battery, the monitor fires up and gives a super-sharp picture. What we like about this is the wooden base he’s made for the thing, at the same time rough-and-ready, and professional-looking from the outside. It has a routed space for the cables, and once mounted flush with the monitor base and given a bit of wood stain, it looks almost as though it was manufactured that way.

It’s likely most of us won’t find a broadcast viewfinder in the trash, instead settling at best for a little Chinese portable TV. But it’s still interesting to see these unusual devices. Perhaps it might make a good cyberdeck.

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Ebike Display Uses Reflective LCD

Although LCD displays have been used in almost every type of consumer electronics display over the last two decades, many of these screens have a few downsides that limit their usefulness in certain situations. As any owner of an early digital watch, an early laptop, or an early digital camera will testify, these displays often completely fail in direct sunlight. And, a currently new technology often using inexpensive displays in full sunlight conditions is ebikes, so [Volos Projects] decided to use a unique LCD display to solve this issue.

The display is called a reflective LCD (RLCD) and is actually a fairly old but overlooked piece of technology. Displays like these have a reflective layer that bounces ambient light back to the user, increasing contrast and readability in high light, especially when compared to more common transmissive displays. This build is based on a board from Waveshare, which includes the screen and its driver components, and [Volos Projects] integrated this into a test stand that mimics an ebike’s speed sensor and other hardware like turn signals. The display shows the bike’s speed and a few other indicators, and thanks to the screen, this information can be easily seen in full sun.

Although he doesn’t have it on an actual e-bike yet, he hopes it will be useful for those who want to try out something like this with their substandard e-bike displays. The code he’s used is available on a GitHub page for anyone interested. We’d imagine that a low-cost display like this would pair well with an open-source ebike like this one.

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E-paper Dashboard Reimagines Smart Home’s Connection With Technology

When [Joel Hawksley] and his partner got married, they had a goal to create a home with a healthy relationship to technology, which largely means avoiding smartphone use. Smartphones aren’t without their benefits, though, like being clocks and calendars, so [Joel] started looking for other options to replace these capabilities. At first he went with a “magic mirror” solution, but quickly pivoted to a wall-mounted e-paper solution he calls Timeframe which has evolved into a respectable overview for his home and life.

E-paper has a number of advantages over LCD and LED displays, one of which being that its resemblance to real paper makes it feel more organic. The first e-paper iterations of Timeframe used multiple displays in wooden frames, and [Joel] had a few different ones stationed around the house. They received their data from a custom-built Rails backend which sent pictures to the devices. This made the refresh rate possible fairly low, but a new 23.5″ display from Boox eventually enabled an acceptably high resolution and refresh rate which could support more traditional display uses. But this display required that [Joel] rewrite the entire back-end, an effort that took quite a bit of time but resulted in an impressive final product.

Like any custom-built project like this, [Joel] still has plans for improvements including those around further integration with his Home Assistant and reducing costs for future platforms. E-paper displays are popular pieces of technology for home dashboards like this, in the past we’ve seen similar, smaller builds which coincidentally have the same name.