Mechanical 7-Segment Display Looks Clean

[Jens] wanted a subscriber counter for his YouTube channel. He could have gone with a simple OLED, LCD, or LED display, but he wanted something more tactile and interesting. So he built a mechanical 7-segment display instead!

Currently, [Jens]’s channel is in the four-digit subscriber range, so he planned to build a four-digit display. He started by searching for existing projects in this space, and came across the designs of [shiura] on Thingiverse. [shiura] had a 3D printed cam-driven 7-segment digit that runs on a single servo motor. Once armed with four of the digits, he hooked them up to a Pi Pico W to drive them all with four servo outputs. The Pico W is responsible for querying the channel subscriber count online, and updating the display in turn.

It’s a neat build, and [Jens] learned some things along the way—like how Super Lube seemed to ruin filament for him. Ultimately, the build came good, and it looks great. We’ve seen some other mechanical 7-segment builds before, too!

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An image of an orange, translucent glowing quartz rod. Thermocouples can be seen at intervals along the rod looking in.

Industrial Solar Heat Hits 1000˚C

While electricity generation has been the star of the energy transition show, about half of the world’s energy consumption is to make heat. Many industrial processes rely on fossil fuels to reach high temps right now, but researchers at ETH Zurich have found a new way to crank up the heat with a solar thermal trap. [via SciTechDaily]

Heating water for showers or radiant floor systems in homes is old hat now, but industrial application of solar power has been few and far between. Part of the issue has been achieving high enough temperatures. Opaque absorbers can only ever get as hot as the incident surface where the sun hits them, but some translucent materials, like quartz can form thermal traps.

In a thermal trap, “it is possible to achieve temperatures that are higher in the bulk of the material than at the surface exposed to solar radiation.” In the study, the researchers were able to get a 450˚C surface to produce 1,050˚C interior temperature in the 300 mm long quartz rod. The system does rely on concentrated solar power, 135 suns-worth for this study, but mirror and lens systems for solar concentration already exist due to the aforementioned electrical power generation.

This isn’t the only time we’ve seen someone smelting on sunlight alone, and you can always do it less directly by using a hydrogen intermediary. If you’re wanting a more domestic-level of heat, why not try the wind if the sun doesn’t shine much in your neighborhood?

Ribbon Cable Repair Saves Touch ID

Some might consider a broken ribbon cable to be unsalvagable. They’re delicate and fragile as can be, and sometimes just fussing with them further is enough to cause additional damage. However, with the right set of skills, it’s sometimes possible to achieve the unthinkable. As [Master Liu] demonstrates, you can indeed repair a broken ribbon cable, even a tiny one.

The video concerns a ribbon cable linked to a Touch ID fingerprint sensor from an Apple device. It’s common to break these ribbon cables when repairing a phone, and doing so causes major problems. The Touch ID device is paired with the host phone, and cannot easily be replaced. Thus, repair is justified if at all possible.

The repair involves scraping back the outer coating on the two sections of ribbon cable to reveal the copper pads underneath. The copper is then coated with flux and solder to prepare them to be rejoined. Ultra-fine strands of wire are used to join the individual traces. Then, the repaired section is coated in some kind of sealant or epoxy to hold the joint together and protect it from failing again. The theory is easy, it’s just the execution that’s hard.

Ribbon cable repair is becoming one of our favorite topics of late. Sometimes you just need a steady hand and the guts to have a go. Video after the break.

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Home Automation Terminal Has Great Post-Apocalyptic Look

If you use home automation these days, you’re probably used to using smart speakers, your smartphone, or those tabletop touchscreen devices. If you wanted something cooler and more personal, you could try building something like [Rick] did.

A Raspberry Pi 400 is the basis for the machine, and it still uses the original keyboard. It’s paired with a 3D-printed shell with a 7″ Waveshare HDMI touch display in it. The LCD is placed behind a Fresnel lens which provides some magnification. It displays a glowing blue command line which accepts text commands. It’s hooked up to the OpenAI API, so it’s a little smarter than just any old regular terminal. It’s hooked up to [Rick’s] home automation system, so he can use natural language queries to control lighting, music, and all the rest. Think Alexa or Siri, but in text form.

The design of the case, with its rounded edges, vents, and thick bezels gives it a strong retro-futuristic look, reminiscent of something out of Fallout. [Rick’s] neat application of weathering techniques helped a lot, too.

It reminds us of some of the cooler Pip Boy builds we’ve seen. Meanwhile, if you’ve got your own creative terminal build in the works, don’t hesitate to drop us a line!

Tabletop Handybot Is Handy, And Powered By AI

Decently useful AI has been around for a little while now, and robotic arms have been around much longer. Yet somehow, we don’t have little robot helpers on our desks yet! Thankfully, [Yifei] is working towards that reality with Tabletop Handybot.

What [Yifei] has developed is a robotic arm that accepts voice commands. The robot relies on a Realsense D435 RGB-D camera, which provides color vision with depth information as well. Grounding DINO is used for object detection on the RGB images. Segment Anything and Open3D are used for further processing of the visual and depth data to help the robot understand what it’s looking at. Meanwhile, voice commands are interpreted via OpenAI Whisper, which can feed prompts to ChatGPT for further processing.

[Yifei] demonstrates his robot picking up markers on command, which is a pretty cool demo. With so many modern AI tools available, we’re getting closer to the ideal of robots that can understand and execute on general spoken instructions. This is a great example. We may not be all the way there yet, but perhaps soon. Video after the break.

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Linux Fu: The Root Cause

There was a time when real system administrators just logged into Unix systems as root. But as we all know — with great power comes great responsibility. It’s too easy to do terrible things when you are really just trying to do normal work, and, on top of that, malicious software or scripts can do naughty things without you noticing. So common practice quickly changed to where an administrator had a personal account but then had a way to run certain programs “as root” which means you had to deliberately decide to wield your power.

Before long, people realized you don’t even need a root login account. That way, an attacker can’t try to log into root at all. Sure, they could still compromise your account, but a random hacker knows you might have a root user, but it is harder to guess that your login ID is JTKirkJr or whatever.

There are other ways to control what users can do, but many Linux and Unix installations still use this model. The root can do everything but login, and specific users get the privilege to do certain things.

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This MIDI BoomBox Takes Floppies

You might have had a boombox back in the 1990s, but probably not like the Yamaha MDP-10. As [Nicole] explains, the odd little device played MIDI files from a floppy disk. Technically, it wasn’t truly a boombox because it lacked batteries, but it sure looks like one.

The box also had a MIDI input jack, but no output. For an antique gadget, it is pretty impressive, but maybe not much by today’s standards. Of course, what we really wanted to see was what was inside. [Nicole] doesn’t disappoint.

The boombox brains are a pair of Hitachi H8 3000-series CPUs. The boards actually looks surprisingly modern until you notice the lack of integration. There are separate ROMs, RAMs, a floppy drive controller, and, of course, MIDI chips. Apparently, opening the box up is a challenge so [Nicole] suggests not doing it unless necessary. We assume it went back together with no problems.

There are lots of tidbits about peculiarities in the device. There are also, of course, recordings of the output and some comparisons from other devices. A great look into an old and odd piece of gear.

Since it has an input jack, you could connect it to — oh, we don’t know — maybe some spoons? Or a hurdy-gurdy.