Pulling Music Out Of Thin Air with a Raspberry Pi

Pianos are great instruments, but being rather heavy and requiring a fair amount of space they are certainly not known for their convenience. Sure, there are more portable varieties available, but they rarely resemble the elegance and classiness of a grand piano. One option is of course to build a downscaled version yourself — and since you’re already customizing the instrument, why stop at the way you play it. [2fishy] didn’t stop there either and ended up with a wooden, space friendly, light controlled piano housing a Raspberry Pi.

Inspired by the concept of a laser harp, [2fishy] followed the same principle but chose a simpler and safer alternative by using LEDs instead. For each playable tone, a LED is mounted opposite a light dependent resistor, creating an array of switches that is then connected to the Raspberry Pi’s GPIO pins. A Python script is handling the rest, polling the GPIO states and — with a little help from pygame, triggering MIDI playback whenever the light stream is interrupted.

There are enough LED/LDR pairs to play one full octave and have some additional control inputs for menu and octave shifting. This concept will naturally require some adjustments to your playing — you can get an idea of it in the demonstration video after the break. And if this design is still not the right size for you, or if you prefer to play in total darkness, this similar MIDI instrument using ultrasonic distance sensors could be of interest.

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AT-ST High Chair Elevates Lucky Jedi Youngling

As a new parent, there’s lots you have to do. You have to buy a car seat, get the baby’s room ready, figure out daycare; all the boring but unavoidable minutiae of shepherding a tiny human. But for the more creative types, that list might include warming up the 3D printer or putting a fresh bit in the CNC, as there’s no better way to welcome a little one into the world than giving them some custom gear to get started with.

That’s certainly been the plan for [Matthew Regonini], who’s been showering his son with DIY playthings. He recently wrote in to tell us about his awesome AT-ST high chair build that manages to turn the drudgery of getting a baby to eat into an epic worthy of a John Williams score.

This isn’t the first time [Matthew] has turned dead trees into Imperial hardware. Last year we covered his fantastic AT-AT rocker which utilized the same construction techniques. The parts are cut out of plywood with his CNC, separated, cleaned up on a spindle sander, and finally assembled with wood glue and a few strategic fasteners. The depth and level of detail he’s able to achieve when the individual pieces are stacked up is exceptionally impressive. If builds like these don’t get you thinking about adding a CNC to your workshop, nothing will.

As with the AT-AT, the finish on the high chair is simply a healthy application of polyurethane. This keeps the wood from being porous (important as this build will be seeing its fair share of food and liquids) while retaining a natural look. Some might be tempted to paint it up in appropriate Imperial colors, but that might be a bit imposing considering its intended occupant.

Really, the only downside with this build is how quickly his son will outgrow it. The obvious solution to the problem is a constant supply of fresh babies to pilot it, but that’s one type of creation that we don’t generally detail here on Hackaday. If you have questions, ask your parents.

Incidentally, it’s starting to look like we’ve got a plywood arms-race going on. We’re excited to see somebody take it to the next level. A little scared, but mainly excited.

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Interactive LED Table

Some hackers make functional things that you can’t allow to be seen in polite company. Others make beautiful things that could come from a high-end store. [Marija] falls into the second category and her interactive LED coffee table would probably fetch quite a bit on the retail market. You can see a video of the awesome-looking table, below.

It isn’t just the glass, MDF, and pine construction. There’s also a Bluetooth interface to a custom Android application from [Dejan], who collaborated on the project. However, if you aren’t comfortable with the woodworking, [Marija’s] instructions are very detailed with great pictures so this might be a good starter project.

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Getting to Know an 18th Century Hacker

Here at Hackaday we tend to stay pretty close to the bleeding edge in tech, not by any conscious effort, but simply because that’s what most hackers are interested in. Sure we see the occasional vintage computer rebuild, or reverse engineering of some component that was put into service before most of us were born; but on the whole you’re way more likely to see projects involving the latest and greatest microcontroller to hit AliExpress than ones involving the once ubiquitous vacuum tube.

Bill Maddox

But occasionally it’s nice to take a step back from the latest and greatest, to really look at what makes the hacker spirit without the all modern trappings of blinking LEDs and Wi-Fi connectivity. We make and explore because it’s something we are passionate about, and while today most of us are doing that with a soldering iron or a compiler, that hasn’t always been the case. In the video below, historic interpreter and woodworker [Bill Maddox] talks about what draws him to 18th century technology. His tools may look foreign to us, but the passion he shows while talking about his creations will be familiar to anyone who’s ever set foot in a hackerspace.

Even with a vastly different set of interests than the modern hacker, [Bill] runs into some very familiar problems. When the highly specialized tools he needed to work like an 18th century craftsman weren’t available, he decided to make his own. But to make his own tools he needed to learn how to forge, and after he forged his hand tools he moved on to forging chisels for the lathe he decided to build.

Whether or not we ever take a knife to a piece of wood and try to carve out a spoon, it’s impossible to watch [Bill] speak about his creations and not see him as a kindred spirit. Like many of us, he’s honed skills in a niche that the everyday person takes for granted. Makes you wonder what people from 300 years in the future would think of us if they could peer back through the centuries.

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Smartphone Controlled Periodic Table of Elements

It wouldn’t be much of a stretch to say that here at Hackaday, we’re about as geeky as they come. Having said that, even we were surprised to hear that there are people out there who collect elements. Far be it from us to knock how anyone else wishes to fill their days, but telling somebody at a party that you collect chemical elements is like one step up from saying you’ve got a mold and fungus collection at home. Even then, at least a completed mold and fungus collection won’t be radioactive.

But if you’re going to spend your spare time working on a nerdy and potentially deadly collection, you might as well put it into an appropriate display case. You can’t just leave your Polonium sitting around on the kitchen counter. That’s the idea behind the interactive periodic table built by [Maclsk], and we’ve got to admit, if we get to put it in a case this awesome we might have to start our own collection.

A large portion of this project is building the wooden display case itself as, strangely enough, IKEA doesn’t currently stock a shelving unit that’s in the shape of the periodic table. The individual cells and edge molding are made of pine, the back panel is MDF, and the front of the display is faced off with thin strips of balsa to cover up all the joints. Holes were then drilled into the back of each cell for the LED wiring, and finally the entire frame was painted white.

Each cell contains an WS2812B RGB LED, which at maximum brightness draws 60mA. Given the 90 cells of the display case, [Maclsk] calculated a 5.4A power supply would be needed to keep everything lit up. However, he found a 4A power supply that made his budget happier, which he reasons will be fine as long as he doesn’t try to crank every cell up to maximum at the same time. Control for the display is provided by an Arduino Nano and HC05 Bluetooth module.

The final piece of the project was the Android application that allows the user to control the lighting. But it doesn’t just change colors and brightness, it’s actually a way to visualize information about the elements themselves. The user can do things like highlight certain groups of elements (say, only the radioactive ones), or light up individual cells in order of the year each element was discovered. Some of the information visualizations are demonstrated in the video below, and honestly, we’ve seen museum displays that weren’t this well done.

We last caught up with [Maclsk] when he created a very slick robotic wire cutting machine, which we can only assume was put to work for this particular project. Too bad he didn’t have a robot to handle the nearly 540 soldering joints it took to wire up all these LEDs.

[via /r/DIY]

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DIY Bookshelf is More Than Meets The Eye

It might surprise you, Dear Reader, that not every project featured on Hackaday needs to pulsate with LEDs, or update the world about its goings-on over Twitter. They don’t even, contrary to what you may have heard, need to have an Arduino inside. No, sometimes you can pull off a pretty neat hack with nothing more than some wood, a couple of tools, and a unique idea which repurposes something that would otherwise be in a landfill.

Such is the case with the latest project from [Keith Decent], which uses plywood and the spines of old books to create a secret compartment “bookshelf”. The concept is probably best described as a roll-top desk on its side, and while the action does appear a little stiff, it scores extra points for how easy it looks to replicate.

Using a router, [Keith] cuts a channel into the top and bottom sheets of plywood, which the “books” will eventually ride in. This channel goes around the entire perimeter of the shelf, and it’s important to make it as straight as possible so nothing binds up. To make sure things move through as smoothly as possible, some sandpaper is used to clean-up the inside edges.

The next step is to rip some books apart and salvage their spines. Used books can be purchased for next to nothing at flea markets, so even if you don’t have a home library filled with vintage tomes to eviscerate, it should be easy enough to get your hands on some if you want to build your own version. For sanity’s sake it would seem that books with the same size spines are ideal, so keep an eye out for old sets of encyclopedias and the like.

When the spines are removed from the books, they get glued to individual wooden slats. These slats then have holes drilled in the top and bottom, and standard wood screws driven in to act as “rollers”. Real rollers would undoubtedly make for smoother action, but you can’t beat his method if you’re trying to get it done cheaply and quickly.

The slats are then glued onto a piece of fabric, creating what is referred to as a tambour. The fabric backing links all the slats together and makes it so that pushing and pulling one slat will move them all together as one. The book spine tambour is then inserted in the routed channel, and the back panel of the shelf can be installed to lock it all together.

At this point the project is essentially done, but [Keith] does take it the extra mile by sealing all the book spines and doing some finish work on the shelf to make it look more like a real vintage piece of furniture instead of some scrap plywood screwed together.

If this exercise in woodworking has gotten you interested in the wonderful world of dead trees, you’re in luck. We’ve covered several woodworking projects from the hacker perspective, so you won’t be completely lost.

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Robotic Table Saw Automates Finger Joints

We’ve all seen finger joints or box joints, those interlocking puzzle pieces that make laser-cut plywood enclosures such a fixture for DIY projects. But laser cutters make finger joints look much easier to fabricate than they are with traditional woodworking tools, which often lead to disappointing results.

But this finger joint cutting robot is no traditional woodworking tool, and [timschefter] put a lot of work into building the rig. We have to admit that when we first saw the video below, the thought of having a table saw in our shop that could be turned on with a button on a phone gave us pause. But on closer analysis, it looks like safety was a major concern with this build. With a prominent e-stop and an interlock switch, the small table saw that forms the foundation of the robot should be safe enough. On the table top is a sled with a linear slide that moves the workpiece perpendicular to the blade, and the sled moves back and forth over the blade with pneumatic cylinders. The joint is set up with a custom app which calculates the pin width and spacing, which can be evenly distributed across the panel, or, for a bit of geeky fun, controlled to make a joint that encodes a message in Morse.

A lot of work went into this, and while it’s not the first robotic finger joint cutter we’ve seen, it’s pretty impressive. Now if it could only automate dovetails.

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