Raspberry Pi Creates Melody

March 28, 2022 by Bryan Cockfield 2 Comments

For those who are not into prog rock in the 70s or old radio shows from the 40s, the Theremin may be an unfamiliar musical instrument. As a purely electronic device, it’s well outside the realm of conventional musical instruments. Two radio antennas detect the position of the musician’s hands to make a unique sound traditionally associated with eeriness or science fiction.

Normally a set of filters and amplifiers are used to build this instrument but this build instead replaces almost everything with a Raspberry Pi Zero 2, and instead of radio antennas to detect the position of the musician’s hands a set of two HC-SR04 distance sensors are used instead. With the processing power available from the Pi, the modernized instrument is able to output MIDI as well which makes this instrument easily able to interface with programs like GarageBand or any other MIDI-capable software.

The project build is split into two videos, the second of which is linked below. The project code is also available on the project’s GitHub page, so anyone with the Pi and other equipment available can easily start experimenting with this esoteric and often overlooked musical instrument. It’s been around for over 100 years now, and its offshoots (including this build) are as varied as the sounds they can produce.

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The octagonal wooden box described in the project. On the left, outer surface of the box is shown, with "Say Friend And Come In" inscription, as well as a few draings (presumably from Lord of The Rings) and two metallic color stars that happen to serve as capacitative sensor electrodes. On the right, underside of the lid is shown, with all the electronics involved glued into CNC-machined channels.

Say Friend And Have This Box Open For You

March 28, 2022 by Arya Voronova 13 Comments

Handcrafted gifts are special, and this one’s no exception. [John Pender] made a Tolkien-inspired box for his son and shared the details with us on Hackaday.io. This one-of-a-kind handcrafted box fulfills one role and does it perfectly – just like with the Doors of Durin, you have to say ‘friend’ in Elvish, and the box shall unlock for you.

This box, carefully engraved and with attention paid to its surface finish, stands on its own as a gift. However, with the voice recognition function, it’s a project complicated enough to cover quite a few fields at once – woodworking, electronics, and software. The electronics are laid out in CNC-machined channels, and LED strips illuminate the “Say Friend And Come In” inscriptions once the box is ready to listen. If you’re wondering how the unlocking process works, the video embedded below shows it all.

Two solenoids keep the lid locked, and in its center is a Pi Zero, the brains of the operation. With small batteries and a power-hungry board, power management is a bit intricate. Two capacitive sensors and a small power management device are always powered up. When both of the sensors are touched, a power switch module from Pololu wakes the Pi up. It, in turn, takes its sweet time, as fully-fledged Linux boards do, and lights up the LED strip once it’s listening.

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Tiny Pinball Is As Cute As Pi

March 27, 2022 by Matthew Carlson 8 Comments

Pinball machines are large, complex, and heavy boxes of joy and delight. However, when you don’t have the money or space for one, you have to make your own mini Raspberry Pi-powered one.

With access to a local makerspace and a bit of extra free time, [Chris Dalke] had plans to capture the flavor of a full-scale pinball machine in a small package. Laser-cut Baltic birch forms the enclosure, and a screen makes up the playing field rather than a physical ball. An Arduino Uno handles the three buttons, the four LED matrixes, and a solenoid for haptic feedback, communicating

with the Pi via serial. Unfortunately, even with a relatively decent

volume inside, it is still a tight squeeze.

Rather than use an off-the-shelf pinball game, [Chris] wrote his own in C using raylib and raygui, two handy libraries that can be included in the project quickly. SQLLite3 writes high scores out to disk. All in all, an inspiring project that has a very high level of polish.

If you’re looking for a tiny pinball machine but want more of the classic pinball feel, why not look at this scale pinball machine?

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Get GitHub Tickets IRL With A Raspberry Pi And A Receipt Printer

March 25, 2022 by Dan Maloney 15 Comments

Thermal receipt printers are finding their way into all sorts of projects that are well beyond the point-of-sale environment that they normally inhabit. And while we applaud all the creative and artistic uses hackers have found for these little gems, this GitHub physical ticket printer has to be the best use for one yet.

According to [Andrew Schmelyun], seeing a fast-food order pop up on a thermal printer was the inspiration for this build. Maintaining over one hundred GitHub repos as he does, it’s easy for the details of any one bug report or feature request to get lost in the swarm of sticky notes that [Andrew] previously used to keep track of his work. To make it happen, he teamed an Epson thermal printer up to a Raspberry Pi Zero W and worked out the details of sending data to the printer using PHP. Luckily, there’s a library for that — the beauty of GitHub.

With the “Hello, World!” bit out of the way, [Andrew] turned his attention to connecting to GitHub. He set up some webhooks on the GitHub side to send a POST request every time an issue is reported on one of his repos. The POSTs are sent via ngrok to a PHP web server running on the Pi, which formats the data and sends the text to the printer. There’s a short video in the tweet below.

Between the sound of the printer working and the actual dead-tree ticket, it’ll be hard for [Andrew] to miss issues now. We’ve seen thermal printers stuffed into cameras, used to send pictures to Grannie, and even watched them commit suicide slowly, but we say hats off to [Andrew] for his solid work ethic and a fun new way to put a receipt printer to use.

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DIY SLS 3D Printer Getting Ready To Print

March 25, 2022 by Dave Rowntree 12 Comments

Ten years ago the concept of having on our desks an affordable 3D printer knocking out high quality reproducible prints, with sub-mm accuracy, in a wide range of colours and material properties would be the would be just a dream. But now, it is reality. The machines that are now so ubiquitous for us hackers, are largely operating with the FDM principle of shooting molten plastic out of a moving nozzle, but they’re not the only game in town. A technique that has also being around for donkeys’ years is SLS or Selective Laser Sintering, but machines of this type are big, heavy and expensive. However, getting one of those in your own ‘shop now is looking a little less like a dream and more of a reality, with the SLS4All project by [Tomas Starek] over on hackaday.io.

[Tomas] has been busy over the past year, working on the design of his machine and is now almost done with the building and testing of the hardware side. SLS printing works by using a roller to transfer a layer of powdered material over the print surface, and then steering a medium-power laser beam over the surface in order to heat and bond the powder grains into a solid mass. Then, the bed is lowered a little, and the process repeats. Heating of the bed, powder and surrounding air is critical, as is moisture control, plus keeping that laser beam shape consistent over the full bed area is a bit tricky as well. These are all hurdles [Tomas] has to overcome, but the test machine is completed and is in a good place to start this process control optimisation fun. Continue reading “DIY SLS 3D Printer Getting Ready To Print” →

PiSpy, The Camera Setup Designed To Make Biological Observations Better

March 24, 2022 by Dan Maloney 3 Comments

Back in grad school, we biology students were talking shop at lunch one day. We “lab rats” were talking about the tools of the trade, which for most of us included things like gel electrophoresis, restriction endonucleases, and polymerase chain reaction. Not to be left out, a fellow who studied fire ants chimed in that his main tool was a lawn chair, which he set up by a Dumpster in a convenience store parking lot to watch a fire ant colony. Such is the glamor of field biology.

Ants on the march. Tough luck for the crickets, though.

What our colleague [Mike] wouldn’t have given for something like PiSpy, the automated observation tool for organismal biology by [Greg Pask] of Middlebury College, et al. As discussed in the preprint abstract, an automated imaging platform can be key to accurate observations of some organisms, whose behavior might be influenced by the presence of a human observer, or even a grad student in a lawn chair. Plus, PiSpy offers all the usual benefits of automation — it doesn’t get tired, it doesn’t need to take bathroom breaks, and it can even work around the clock. PiSpy is based on commonly available components, like laser-cut plywood and a Raspberry Pi and camera, so it has the added advantage of being cheap and easy to produce — or at least it will be when the Pi supply picks back up again. PiSpy takes advantage of the Pi’s GPIO pins to enable triggering based on external events, or controlling peripherals like lights or servos.

While built for biological research, there are probably dozens of uses for something like PiSpy. It could be handy for monitoring mechanical testing setups, or perhaps for capturing UI changes during embedded device development. Or you could just use it to watch birds at a feeder. The source is all open-sourced, so whatever you make of PiSpy is up to you — even if it’s not for watching fire ants.

A Macintosh-inspired desk ornament, next to a sceenshot of a classic Macintosh computer desktop

‘Desk Accessory’ Pays Homage To Macintosh

March 21, 2022 by Chris Wilkinson 9 Comments

The retrocomputing community are experts at keeping vintage Apple iron running, but if you’re looking for a simpler way to pay homage to the original Mac, check out this Raspberry Pi powered ‘desk accessory’ by [John Calhoun], fittingly called ‘SystemSix’.

Housed inside a delightfully Mac-shaped piece of laser-cut acrylic, SystemSix is powered by as Raspberry Pi 3, with the graphics displayed on a sizeable 5.83″ e-ink panel. While it resembles a kind of retro-futuristic take on the ‘classic’ Macintosh, SystemSix is the illusion of a fully interactive computer. While non-interactive, the fake desktop is every bit as charming as a real Macintosh display, albeit scaled down. The desktop updates automatically with new information, and presently includes a calendar, dithered lunar phase graphic, and a local weather report.

Clearly calling it a ‘desk accessory’ is a neat play on words. The original Macintosh implemented simple desk accessory programs, such as the calculator and alarm clock, that could run alongside the main application in memory. This was the only way to run more than one application on the Macintosh, before MultiFinder added rudimentary cooperative multitasking in 1987. As such, SystemSix is a functional, stylish and quite literal ‘desk accessory’.

[John] has the full project write-up over on GitHub, and goes into great detail about maintaining the Macintosh aesthetic. For example, the lunar phase graphic uses ‘Atkinson’ dithering. This technique was pioneered by Apple programmer Bill Atkinson, the author of MacPaint and the QuickDraw toolbox on the original Macintosh (and later, Hypercard).

And in case you were wondering – yes, this is the [John Calhoun], who programmed Glider for Macintosh. Now recently retired from Apple, we’re really excited to see what other Macintosh-inspired creations he comes up with. Maybe he will come back around to his Mac-powered MAME cabinets that we covered all the way back in 2005. Or perhaps a sleeper battlestation, like the iMac G4 lampshade that was upgraded with an M1 processor.