Screenshot of the website, showing the sidebar with technology types on the left, and an entry about modifying LCD polarizers on the right, with a video showing an art piece using LCD polarizers

Alternative Display Technologies And Where To Find Them

June 1, 2022 by Arya Voronova 13 Comments

[Blair Neal] has been working on an information database for artists and hackers – a collection of non-conventional display technologies available to us. We’ve covered this repository before, six years ago – since then, it’s moved to a more suitable platform, almost doubled in size, and currently covers over 40+ display technology types and related tricks. This database is something you should check out even if you’re not looking for a new way to display things right now, however, for its sheer educational and entertainment value alone.

[Blair] doesn’t just provide a list of links, like the “awesome-X” directories we see a lot of. Each entry is a small story that goes into detail on what makes the technology tick, its benefits and fundamental limitations, linking to illustrative videos where appropriate. It’s as if this guide is meant to give you an extensive learning course on all the ways you can visualize things on your creative journey. All of these categories have quite a few examples to draw from, highlighting individual artworks that have made use of any technology or trick in a particular way.

If you’re ever wondered about the current state of technology when it comes to flexible or transparent displays, or looked for good examples of volumetric projection done in a variety of ways, this is the place to go. It also talks about interesting experimental technologies, like drone displays, plasma combustion or scanning fiber optics. Overall, if you’re looking to spend about half an hour learning about all the ways there are to visualize something, this database is worth a read. And, if there’s a display technology the author might’ve missed and you know something about, contributions are welcome!

Someone setting out to compile information about an extensive topic is always appreciated, and helps many hackers on their path. We’ve seen that done with 3D printer resin settings and SMD part codes, to name just a few. What’s your favourite hacker-maintained database?

Bottoms Up: Soda Can Help With Almost Any Project

May 26, 2022 by Kristina Panos 32 Comments

If there’s any one thing that the average hacker is short on at a given moment (besides chips), it’s transient small part storage. Just as new projects are built from small parts, diagnostics and teardowns of commercial equipment invariably result in small parts. We think [amenjet] may have the answer — small parts holders made from the bottoms of soda cans.

You start by cutting the bottom off of an empty can however you like. In the first video after the break, [amenjet] scores the can on what could be a purpose-built jig before cutting along the line with tin snips, but you could use regular scissors if that’s all you have. Then it’s just a matter of shoving it into the circle around the perimeter of the print to secure the sharp edge.

The underside of the print is graduated and ends with a small hole fit for a disc magnet. To keep the prints from scratching the table, [amenjet] covered the bottoms with crushed velvet. After making about a dozen of these things, they CNC’d a tray to hold three of them, which you can see in the second video. Each cavity in the tray is lined with more crushed velvet for elegance and stability.

Between the concavity of the can bottom and that little lip, it should be particularly easy to actually retrieve a tiny part from the pile and grab on to it. Between the utility and the recycled aspect, this could easily be an entry into the second Challenge of the 2022 Hackaday Prize, which runs now until Sunday, June 12th. This round is all about reusing, recycling, and revamping anything and everything to keep it out of the landfill. Start your entry today!

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The STM32 Makes For A Cheap DIY USB Soundcard

May 24, 2022 by Lewin Day 14 Comments

Soundcards used to be giant long 8-bit ISA things that would take up a huge amount of real estate inside a desktop computer. These days, for most of us, they’re baked into the motherboard and we barely give them a second thought. [Samsonov Dima] decided to whip up a cheap little sound card of their own, however, built around the STM32.

The soundcard is based specifically on the STM32F401. readily available on the “Green Pill” devboards. A digital-to-analog converter is implemented on the board based on two PWM timers providing high-quality output. There’s also a simulated software sigma delta ADC implemented between the audio streaming in via USB and the actual PWM output, with some fancy tricks used to improve the sound output. [Samsonov] even found time to add a display with twin VU meters that shows the audio pumping through the left and right channels.

Without test gear on hand, we can’t readily quantify the performance of the sound card. However, as per the Youtube videos posted, it appears more than capable of recreating music with good fidelity and plenty of fine detail.

If you need a cheap, simple USB sound card that you can hack away on, this might be the one for you. If you need something more suitable for a vintage PC, however, consider this instead. Video after the break.

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PCB Linear Motors For Model Trains

May 19, 2022 by Anne Ogborn 34 Comments

Modeling a railroad is hard. Railroads are large, linear pieces of civil engineering. So many modelers are drawn to the smallest scale they can use. Recently a new scale, named T, at 1:450 has been pushing this barrier. But fitting a reliable mechanical drive mechanism and MCU board in a package this size is a challenge. In practice, even more of a problem is getting reliable electrical contact through a metal wheel on metal track (about the worst possible design for a contact).

T always seemed to us a long way out on the bleeding edge. But all that may have changed. In a recent Hackaday.io writeup, author [Martin] describes a PCB technology based linear motor system to externally drive T scale locomotives.

The system uses 4mm planar coils. The underside of the PCB has another coil, so the effective pitch is 2mm. With microstepping, a step of 0.25mm is possible, and trains run smoothly. Current is 3-400mA. Continue reading “PCB Linear Motors For Model Trains” →

Color(ing) Computer Needs No Batteries

May 18, 2022 by Al Williams 3 Comments

While Radio Shack did have the Color Computer, we don’t think they had this in mind. [Pepepépepe] has some coloring book pages and simple rules that let you simulate logic circuits using a crayon. The downloadable ‘zine has hand-written instructions and several examples.

Keep in mind, this is a computer in the same way the old logic kits in the 1960s were computers. They are really demonstrations of digital logic circuits. To work the “computers”, you pick two colors, one for a square and the other for a circle. You color pathways until you reach a “nory.” The nory, which looks suspiciously like a slingshot with eyes, has a special rule. If both branches of the nory have your circle color on them, the output of the nory will be the square color. Otherwise, the color coming out is the circle color.

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Falling Down The Labyrinth With Wooden Microphone Design

May 17, 2022 by Dan Maloney 7 Comments

It used to be that when we featured one of [Frank Olson]’s DIY ribbon microphone builds, it was natural to focus on the fact that he was building them almost exclusively from wood. But despite how counterintuitive it may seem, and for as many comments as we get that his microphones shouldn’t work without metal in the ribbon motors, microphones like this wooden RCA Model 77 reproduction both look and sound great.

But ironically, this homage features a critical piece that’s actually not made of wood. The 77’s pickup pattern was cardioid, making for a directional mic that picked up sound best from the front, thanks to an acoustic labyrinth that increased the path length for incoming sound waves. [Frank]’s labyrinth was made from epoxy resin poured into a mold made from heavy paper, creating a cylinder with multiple parallel tunnels. The tops and bottoms of adjacent tunnels were connected together, creating an acoustic path over a meter long. The ribbon motor, as close to a duplicate of the original as possible using wood, sits atop the labyrinth block’s output underneath a wood veneer shell that does its best to imitate the classic pill-shaped windscreen of the original. The video below, which of course was narrated using the mic, shows its construction in detail.

If you want to check out [Frank]’s other wooden microphones, and you should, check out the beautiful Model 44 replica that looks ready for [Sinatra], or the Bk-5-like mics he whipped up for drum kit recording.

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Vicious Little Desktop Shredder Pulverizes Plastic Waste

May 15, 2022 by Dan Maloney 21 Comments

We’ve all likely seen video of the enormous industrial shredders that eat engine blocks for lunch and spit out a stream of fine metal chips. The raw power of these metal-munching monsters is truly fearsome, and they appear to be the inspiration for SHREDII, the miniature plastic shredder for at-home recycling of plastic waste.

The fact that SHREDII isn’t all that large doesn’t make it any less dangerous, at least to things smaller and softer than engine blocks, like say fingers. The core of the shredder is a hexagonal axle carrying multiple laser-cut, sheet steel blades. The rotating blades are spaced out along the axle so they nest between a bed of stationary blades; rotating the common axle produces the shearing and cutting action needed to shred plastic.

On version one of the shredder, each blade had two hooked teeth, and the whole cutting head was made from relatively thick steel. When driven by a NEMA 34 stepper — an admittedly odd choice but it’s what they could get quickly — through a 50:1 planetary gearbox, the shredder certainly did the business. The shreds were a little too chunky, though, so version two used thinner steel for the blades and gave the rotary blades more teeth. The difference was substantial — much finer shreds that were suitable for INJEKTO, their homebrew direct-feed injection molding machine.

There’s a lot to be said for closing the loop on plastics used in desktop manufacturing processes, and the team of SHREDII and INJEKTO stands to help the home gamer effectively reuse plastic waste. And while that’s all to the good, let’s face it — the oddly satisfying experience of watching a shredder like this chew through plastic like it isn’t even there is plenty of reason to build something like this.

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