Detail of an LED display made using ping-pong balls

Modular Design Enables Huge Ping-Pong Ball LED Displays

January 4, 2022 by 22 Comments

Ping-pong balls have many uses: apart from playing table tennis, they have been used for countless art projects, science experiments, and even to raise ships from the bottom of the ocean. As it turns out, they also come in handy as diffusers for LED pixels, allowing the construction of large-size displays without requiring large individual LEDs.

[david] designed an LED ping-pong ball display using 3D printed components, which allows for the construction of arbitrarily-large LED displays thanks to a strictly modular design. The basic unit is a small piece that holds a single LED module and has a cup-like structure for attaching a standard table tennis ball. Twenty-five of these basic units combine together into a panel that also contains wiring ducts. Finally, any number of these panels can be combined into a display, thanks to clips that give the structure rigidity in the out-of-plane direction.

A 3D-printed frame for making an LED display
A single panel holds 25 LEDs and comes with cable ducts. On the right is a clip for connecting multiple frames together.

Of course, simply mounting LED modules is not enough to create a display: the LEDs also need to be connected to power and data lines. [david] didn’t relish the thought of having to cut and strip 1,800 pieces of wire, and therefore devised a clever way of automating this process: he put a bunch of wires onto a piece of card stock and used a laser cutter to burn off the insulation at regular intervals. Then it was simply a matter of soldering these wires onto the LEDs and snipping off pieces along the data bus.

The finished panel is driven by a combination of a Teensy 3.2 to generate the data signals and a Raspberry Pi to process the images. You can see the rather impressive result in the video embedded below; if this inspires you to build your own, you’ll be happy to hear that the STL files and all code are available on [david]’s project page.

Massive LED displays are always fun to watch, and although this is not the first one to use ping-pong balls as diffusers, its modularity and open-source design makes this one perhaps the easiest to replicate. Assuming you have a good supplier of ping-pong balls, of course.

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A homemade seven-segment OLED display

Making OLED Displays In The Home Lab

September 4, 2021 by 13 Comments

Just a general observation: when your project’s BOM includes ytterbium metal, chances are pretty good that it’s something interesting. We’d say that making your own OLED displays at home definitely falls into that category.

Of course, the making of organic light-emitting diodes requires more than just a rare-earth metal, not least of which is the experience in the field that [Jeroen Vleggaar] brings to this project. Having worked on OLEDs at Philips for years, [Jeroen] is well-positioned to tackle the complex process, involving things like physical vapor deposition and the organic chemistry of coordinated quinolones. And that’s not to mention the quantum physics of it all, which is nicely summarized in the first ten minutes or so of the video below. From there it’s all about making a couple of OLED displays using photolithography and the aforementioned PVD to build up a sandwich of Alq3, an electroluminescent organic compound, on a substrate of ITO (indium tin oxide) glass. We especially appreciate the use of a resin 3D printer to create the photoresist masks, as well as the details on the PVD process.

The displays themselves look fantastic — at least for a while. The organic segments begin to oxidize rapidly from pinholes in the material; a cleanroom would fix that, but this was just a demonstration, after all. And as a bonus, the blue-green glow of [Jeroen]’s displays reminds us strongly of the replica Apollo DSKY display that [Ben Krasnow] built a while back. Continue reading “Making OLED Displays In The Home Lab” →

Analog Style VU Meter With Arduino And OLED Display

July 14, 2021 by 20 Comments

Looking for a digital recreation of the classic analog volume unit (VU) meter? If you’ve got an Arduino, a few passive components, and a SSD1306 OLED, then [mircemk] might have the answer for you. As you can see in the video below, his code turns a handful of cheap parts into an attractive and functional audio display.

The project’s Hackaday.IO page explains that the idea is based on the work of [stevenart], with code adapted for the SSD1306 display and some tweaks made to the circuit. While [mircemk] says the code could be modified for stereo as long as the two displays don’t have conflicting I2C addresses, he decided to simply duplicate the whole setup for each channel to keep things simple. With as cheap as some of these parts are nowadays, it’s hard to blame him.

[mircemk] has provided source code for a couple different styles of VU indicators, the colors of which can easily be inverted depending on your tastes. He also clarifies that the jerky motion of the virtual “needle” seen in the video is due to the camera; in real-life it sweeps smoothly like the genuine article.

Much like the project that aimed to recreate authentic “steam gauges” with e-paper displays, this as an excellent technique to file away for use in the future. Compared to authentic analog gauges, these digital recreations are quicker and faster to implement, plus going this route prevents any antique hardware from going on the chopping block.

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Volumetric OLED Display Shows Bladerunner Vibe, Curious Screen Tech

March 4, 2021 by 39 Comments

[Sean Hodgins] is out with his latest video and it’s a piece of art in itself. Beyond a traditional project show and tell, he’s spun together a cyberpunk vibe to premiere the volumetric display he built from an OLED stackup. Update: He’s also documented the build.

The trick of a volumetric display is the ability to add a third dimension for positioning pixels. Here [Sean] delivered that ability with a stack up of ten screens to add a depth element. This is not such an easy trick. These small OLED displays are all over the place but they share a common element: a dark background over which the pixels appear. [Sean] has gotten his hands on some transparent OLED panels and with some Duck-Duck-Go-Fu we think it’s probably a Crystalfontz 128×56 display. Why is it we don’t see more of these? Anyone know if it’s possible to remove the backing from other OLED displays to get here. (Let us know in the comments.)

The rest of the built is fairly straight-forward with a Feather M4 board driving the ten screens via SPI, and an MPU-6050 IMU for motion input. The form factor lends an aesthetic of an augmented reality device and the production approach for the video puts this in a Bladerunner or Johnny Mnemonic universe. Kudos for expanding the awesome of the build with an implied backstory!

If you can’t find your own transparent displays, spinning things are a popular trend in this area. We just saw one last week that spun an LED matrix to form cylindrical display. Another favorite of ours is a volumetric display that spins a helix-shaped projection screen.

Unique LED Display Inspired By Fighter Jet Dashboard

August 22, 2020 by 6 Comments

Last year, [Mangy_Dog] was asked by a few friends to consult on a project they were working on. The goal was to build an authentic replica of an F-18 cockpit, apparently for the purposes of creating a film. The project never materialized, but it did inspire him to take a hard look at the 1970s era alphanumeric displays utilized in the real aircraft. One thing lead to another, and he ended up using his own take on the idea to build his own “starburst” digit display.

As [Mangy_Dog] explains, while the faces of these original displays might have been quite small, there was a lot going on behind the scenes. Due to the technical limitations of the time, each alphanumeric character was made up of an array of incandescent light bulbs and fiber optic cables. This worked well enough, but was bulky and complex to manufacture.

Today, we can do better, even on the hobbyist level. As it turns out, 0402 LEDs are just about the right size to recreate the segments of the original starburst displays. So [Mangy_Dog] came up with a simple PCB design to not only align the LEDs properly, but drive them with a 74HC595 shift register and an array of MOSFETs. While assembly wasn’t without its challenges, he made good use of his custom built reflow oven to get all the diminutive components in place.

He went through a few different ideas for the diffuser, but eventually settled on black plastic with tiny holes drilled through courtesy of his laser cutter. Behind each set of three holes is a small pocket that got filled from both sides with transparent UV resin, which was then sanded down after curing. The end result isn’t perfect as you can still tell the center dot is brighter than its peers, but the overall effect is still very nice and definitely has a sort of faux-retro appeal.

The military naturally has access to some incredible technology, though they have a tendency to hold onto it for decades. That an individual with a meager budget and homemade tools can improve upon a piece of hardware installed in a $60+ million airplane is a testament to just how fast things are moving.

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Clock Uses Custom LED Displays To Keep Myst Time

January 28, 2020 by 17 Comments

The Myst fans in the audience will love this project because it displays the 25-hour timekeeping system of the D’ni. The hardware hackers will lean a little closer to their screen because it does so with custom made 25-segment LEDs, and the precision obsessed will start breathing heavily when they hear it maintains an accuracy of 0.001 seconds. As for which of those camps creator [Mike Ando] most identifies with, we can’t say. But we definitely respect his style.

We’ll spare you the in-depth description of the base-25 number system apparently used in the Myst franchise. If you’re interested enough you can click on through to the project’s Hackaday.io page and learn how to actually read the clock. Presumably you’ll then come back here and leave your comment in Klingon.

Let’s instead jump right to the part that really gets us excited, those custom displays. To create them, [Mike] cut the face out of black acrylic with a laser, and filled each void with a mixture of clear resin and very fine gypsum plaster. Getting the mix right can be a little finicky as the plaster can clump up, but the end result diffuses the light nicely. The acrylic front panel and a couple of cardboard “gaskets” to keep the light from leaking onto adjacent segments is then stacked on top of a PCB with corresponding 0603 SMD LEDs.

Beyond the soul-crushing number of wires required to hook everything up internally, the rest of the project is relatively straightforward. It uses a WeMos D1 Mini to connect to the WiFi network and pull the current time down from the geographically closest NTP server every couple of hours. Rather than putting a temperature controlled oscillator on the board, [Mike] has decided to pin his accuracy on a constantly on Internet connection and aggressive synchronizations.

From impressive curved bar graph modules to displays segmented with household items, we’ve seen our fair share of custom indicators. But we have to admit that building 25-segment LED displays for the alphabet of a fictional interstellar species sets the bar pretty high.

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Chaining Together A 16×2 Bubble LED Display

December 10, 2019 by 27 Comments

We’ve recently noticed an uptick of interest in so-called “bubble displays”: vintage alphanumeric LEDs which are probably best remembered as being used in watches and calculators before the LCD took over. Today they’re available as surplus or even salvage for literally pennies, but unfortunately they only provide four or five characters to work with. Or rather they did, until [sjm4306] built a board that chains them into a 16×2 array.

For the princely sum of 71 cents each, [sjm4306] picked up ten HPDL-1414 displays, each capable of showing four characters. He then designed a PCB that would accept eight of the displays at once, and even thought ahead to use headers so they could be pulled out and swapped as needed. Of course mounting them is only half the battle, you still need to drive the things.

Each display has its own dedicated driver chip on board, but trying to address each one individually would take far too many pins. So [sjm4306] opted to use a trio of 74HC595 shift registers, allowing him to toggle the three dozen pins necessary over SPI from a microcontroller. He’s even written up a little library and some example code that you can grab on the project’s Hackaday.io page.

Unfortunately, after all his hard work, tragedy struck. As these displays were a couple decades old given their date code, [sjm4306] thought he would clean them up with a bit of alcohol before their big video debut. But whatever plastic the clear panels are made of didn’t take kindly to the IPA, and they all shattered. They still work, but it’s definitely a quirk to keep in mind if you pick up some of these vintage displays to play with yourself.

In the past we’ve seen a much smaller PCB that allowed similar displays to more easily be interfaced with modern microcontrollers; perfect if you just want to bang out a few retro LED characters with a minimum of fuss.

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