What’s Cooler Than A 7-Segment Display? A 7200-Segment Display!

If you look around your desk right now, odds are you’ll see a 7-segment display or two showing you some vital information like the time or today’s weather. But think of how much information you could see with over 1,100 digits, like with [Chris Combs’] 7200-segment display.

For [Chris], this project started the same way that many of our projects start; finding components that were too good of a deal to pass up on. For just “a song or two plus shipping”, he was the proud owner of two boxes of 18:88 7-segment displays, 500 modules in total. Rather than sitting and using up precious shelf space, [Chris] decided to turn them into something fancy he could hang on the wall.

the 7200 segment display grayscaling to show the time
The IS31FL3733 can produce 8 levels of dimming 8-bit PWM, allowing [Chris] to display in grayscale
The first challenge was trying to somehow get a signal to all of the individual segments. Solutions exist for running a handful of displays in one device, but there are certainly no off-the-shelf solutions for this many. Even the possible 16 addresses of the IS31FL3733 driver IC [Chris] chose for this project were not enough, so he had to get creative. Fearing potential capacitance issues with simply using an i2C multiplexer, he instead opted to run 3 different i2C busses off of a Raspberry Pi 4, to interface with all 48 controllers.

The second challenge was how to actually wire everything up. The finished display comes out to 26 inches across by 20.5 inches tall, much too large for a single PCB. Instead, [Chris] opted to design a series of self-contained panels, each with 6 of the display modules and an IS31FL3733 to drive them. While the multiplexing arrangement did leave space for more segments on each panel, he opted to go for this arrangement as it resulted in a nice, clean, 4:3 aspect ratio for the final display.

The end result was a unique and beautiful piece, which Chris titled “One-to-Many”. He uses it to display imagery and art related to the inevitability of automation, machines replacing humans, and other “nice heartwarming stuff like that”, as he puts it. There’a video after the break, but if you are interested in seeing the display for yourself, it will be on display at the VisArt’s Concourse Gallery in Rockville, MD from September 3 to October 17, 2021. More info on [Chris’s] website.

This isn’t [Chris’s] first adventure in using 7-segment displays in such a unique way, click here to read about the predecessor to this project that we covered last year.

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Salvaging Working LEDs From “Dead” Light Bulbs

Sure the box said they would last for years or even decades, but anyone who’s picked up some bargain LED bulbs knows the reality is a bit more complicated. Sometimes a few LEDs in the array pop, reducing the overall light output. More commonly, the power supply starts to fail and the bulb begins to flicker or hum. In either event, you end up pulling the bulb and replacing it.

But [Bifferos] thinks we can do a bit better than that. Rather than just chalking it up to poor QA and tossing the bulb, why not do a little exploratory surgery to identify salvageable LEDs in an otherwise “dead” bulb? After pulling apart a couple of burned out bulbs (name brand and otherwise), he was able to pull out an impressive number of handy LED panels that could be easily repurposed. Naturally, with a little more coaxing, the individual SMD LEDs could be liberated and pushed into service as well.

Separate PCBs with banks of LEDs are ideal for reuse.

As you might expect, there are far too many different LED bulbs out there to create a comprehensive teardown guide, but [Bifferos] does provide some tricks to help get the bulb open without hurting yourself or destroying the thing in the process. Once inside, the design of the bulb will dictate what happens next. Bulbs with multiple arrays of LEDs on their own PCBs can be easily broken down, but if there’s just the single board, you may want to pull the LEDs off individually. To that end, the write-up demonstrates efficient methods of stripping the LEDs using either hot air or a pair of soldering irons.

We’ve talked previously about the rather underwhelming performance of modern LED bulbs compared to the manufacturer’s lofty claims. We’d rather see these bulbs designed well enough that they actually live up to their full potential, but the ability to salvage useful components from the failed luminaries at least softens the blow of having to toss them early. Though that’s not the only reason you should disassemble your LED bulbs before you put them in the trash.

Examples of ZX81 computer game screens

The Labor Of Love That Is Recovering Lost Software

At the beginning of the home computer revolution, the humble compact cassette was far and away the most popular choice for microcomputer data storage, especially on the European continent. As a volunteer at the Museum of Computing, [Keith] was instrumental in recovering and archiving the early works of Roger Dymond, a pioneering developer of early computer software in the United Kingdom.

In his video, [Keith] goes to great lengths detailing the impact that Roger Dymond had on the early home computing scene. After being let go from his council apprenticeship, Roger turned his attention to developing games for the ZX81, and later the ZX Spectrum. With the help of his family, he went on to run a moderately successful mail-order games publishing venture for several years. Increasing advertising costs and a crowded development scene saw Roger’s business become nonviable by 1983, but not before developing several gambling-style games and a standout Space Invaders clone.

Fast forward to 2021, and while some of Roger’s Spectrum software had been archived, much had been marked as ‘missing’ by online archivists. After further research, [Keith] realized that another potentially important tape had been forgotten about. ‘Games Compendium’ for the ZX81 had been completely lost to time, with the only evidence that it had ever existed coming from a 1983 advert in ‘Sinclair User’ magazine. Being written for the earlier model ZX81, the compendium would undoubtedly be of interest to software archivists and game historians.

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Ray Casting 101 Makes Things Simple

[SSZCZEP] had a tough time understanding ray tracing to create 3D-like objects on a 2D map. So once he figured it out, he wrote a tutorial he hopes will be more accessible for those who may be struggling themselves.

If you’ve ever played Wolfenstein 3D you’ll have seen the technique, although it crops up all over the place. The tutorial borrows an animated graphic from [Lucas Vieira] that really shows off how it works in a simplified way. The explanation is pretty simple. From a point of view — that is a camera or the eyeball of a player — you draw rays out until they strike something. The distance and angle tell you how to render the scene. Instead of a camera, you can also figure out how a ray of light will fall from a light source.

There is a bit of math, but also some cool interactive demos to drive home the points. We wondered if Demos 3 and 4 reminded anyone else of an obscure vector graphics video game from the 1970s? Most of the tutorial is pretty brute force, calculating points that you can know ahead of time won’t be useful. But if you stick with it, there are some concessions to optimization and pointers to more information.

Overall, a lot of good info and cool demos if this is your sort of thing. While it might not be the speediest, you can do ray tracing on our old friend the Arduino. Or, if you prefer, Excel.

vektorkollektor-deploy-familyInPark

Vektor Kollektor Inspector

With the world opening up again, [Niklas Roy] and [Kati Hyyppä] have been busy making a public and collaborative project. Meet the Vektor Kollektor, a portable drawing machine experience, complete with a chip-tune soundtrack. It’s great to see public art meet the maker community with zero pretension and a whole lot of fun!

The build started with an HP7475A pen plotter from the 80s, one that was DOA (or was fried during initial testing). [Niklas] and [Kati] kept the mechanism but rebuilt the controls allowing for easy integration with an Arduino Nano and to be powered with a motorcycle battery.

The magic seems to be less in the junk-bin build (which is great) and more in the way this team extended the project. Using a joystick with arcade buttons as an input, they carted Vektor Kollektor to public parks and streets where they invited others to make art. The Kollekted drawings are available on a gallery website in a very cool animated form, freely available for download, on t-shirts, 3D prints, and on coffee mugs because, why not?

Some select drawings are even spray-painted on walls using a large plotter, and we really hope [Niklas Roy] and [Kati Hyyppä] share details on that build soon. Of course this comes hot on the heels of the workshop window cyborg we saw from these two hardware artists.

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ClOCkTAL: For When Reading A Clock Is Just Too Easy

Over on Hackaday.io, [danjovic] presents clOCkTAL, a simple LED clock for those of us who struggle with the very concept of making it easy to read the time. Move aside binary clocks, you’re easy, let’s talk binary coded octal. Yes, it is a thing. We’ll leave it to [danjovic] to describe how to read the time from it:

Do not try to do the math using 6 bits. The trick to read this clock is to read every 3-bit digit in binary and multiply the MSBs by 8 before summing to the LSBs.

Simple. If you’re awake enough, that is. Anyway, we’re a big fan of the stripped-down raw build method using perf board, and scrap wood. No details hidden here. The circuit is straightforward, being based on a minimal configuration needed to drive the PIC16F688 and a handful of LEDs arranged in a 3×4 matrix.

An interesting detail is the use of Bresenham’s Algorithm to derive the one event-per-second needed to keep track of time. And no, this isn’t the more famous Bresenham’s line algorithm you may be more familiar with, it’s much simpler, but does work on the same principle of replacing expensive arithmetic division operations with incremental errors. The original Bresenham’s Algorithm was devised for using with X-Y plotters, which had limited resolution, and was intended to allow movements that were in an imperfect ratio to that resolution. It was developed into a method for approximating lines, then extended to cover circles, ellipses and other types of drawables.

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3d printed GLaDOS home assistant

GLaDOS Voice Assistant Passive-Aggressively Automates Home

With modern voice assistants we can tell a computer to play our favorite music, check the weather, or turn on a light. Like many of us, [nerdaxic] gave in to the convenience and perceived simplicity of various home automation products made by Google and Amazon. Also like many of us, he found it a bit difficult to accept the privacy implications that surround such cloud connected devices. But after selling his Home and Echo, [nerdaxic] missed the ability to control his smart home by voice command. Instead of giving in and buying back into the closed ecosystems he’d left behind, [nerdaxic] decided to open his home to a murderous, passive aggressive, sarcastic, slightly insane AI: GLaDOS, which you can see in action after the break.

Using open source designs from fellow YouTube creator [Mr. Volt], [nerdaxic] 3d printed as much of the GLaDOS animatronic model as he was able to, and implemented much of the same hardware to make it work. [nerdaxic] put more Open Source Software to use and has created a functional but somewhat limited home AI that can manage his home automation, give the weather, and tell jokes among other things. GLaDOS doesn’t fail to deliver some great one liners inspired by the original Portal games while heeding [nerdaxic]’s commands, either.

A ReSpeaker from Seeed Studio cleans up the audio sent to a Raspberry Pi 4, and allows for future expansion that will allow GLaDOS to look in the direction of the person speaking to it. With its IR capable camera, another enhancement will allow GlaDOS to stare at people as they walk around. That’s not creepy at all, right? [nerdaxic] also plans to bring speech-to-text processing in-house instead of the Google Cloud Speech-To-Text API used in its current iteration, and he’s made everything available on GitHub so that you too can have a villainous AI hanging on your every word.

Of course if having GLaDOS looming isn’t enough, you could always build a functional life size Portal turret or listen to the radio on your very own Portal Radio.

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