LMN-3: Putting The ‘OP’ In Open Source Synthesizers

June 14, 2022 by 10 Comments

Some projects you come across simply leave you in awe when you look at the thought and the resulting amount of work that went into it, not only for the actual implementation, but everything around it. Even more so when it’s a single-developer open source project. [Stone Preston]’s synth / sampler / sequencer / DAW-in-a-box LMN-3 absolutely fits the description here, and it seems like he has set his heart on making sure everyone can built one for themselves, by providing all the design files from case down to the keycaps.

The LMN-3 (LMN as in “lemon”, not “comes before the OP“) is intended as a standalone, portable digital audio workstation, and is built around a Raspberry Pi 4 with a HyperPixel display for the user interface. The UI itself, and with it the core part of the software, was created using the Tracktion Engine, which itself uses the JUCE framework and combines your typical synthesizer, sequencer, and sampler features with the DAW part to handle recording, editing, and mixing. The remaining hardware is a custom-designed PCB with a set of function and keyboard buttons, along with a pitch bend joystick and four rotary encoders with push buttons that serve as main input handlers. Oh yes, and a Teensy board.

The UI is actually entirely controlled via MIDI commands, and custom firmware on the Teensy is translating the input events from buttons, encoders, and joystick accordingly. This essentially decouples the hardware from the software, and using a cross-platform framework underneath, you can also run the UI standalone on your computer and use any 3rd-party MIDI controller you like. Or then, as [Stone] thought really about everything, use a hardware emulator he created in addition. You could even leave out the Raspberry Pi and software altogether and turn this into a pure MIDI controller. If that sounds tempting, but you’re looking for something with more knobs and sliders instead of buttons, check out the Traktorino. And if you actually prefer a mouse as input device, there’s always something running in a browser.

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The Weird World Of Liquid Cooling For Datacenters

June 14, 2022 by 42 Comments

When it comes to high-performance desktop PCs, particularly in the world of gaming, water cooling is popular and effective. However, in the world of datacenters, servers rely on traditional air cooling more often than not, in combination with huge AC systems that keep server rooms at the appropriate temperature.

However, datacenters can use water cooling, too! It just doesn’t always look quite how you’d expect.

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Pushing The Limits Of A 16×2 LCD With Bad Apple!!

June 14, 2022 by 20 Comments

While low-contrast, blue-on-slightly-less-blue 16-character by 2-line LCDs are extremely popular, they really are made specifically for alphanumeric use. They do an admirable job of displaying a few characters, but they don’t exactly spring to mind as a display for non-character purposes. But displaying video on a 16×2 LCD is possible, as long as you’re willing to stretch the definition of “video” a bit and use some imagination while watching.

Normally, a 16×2 display can only display a single character in each spot, chosen from a fixed character set. But [arduinocelantano] was able to leverage the eight custom character slots the display allows to build up images from arbitrary 5×8 pixel bitmaps. After using ffmpeg to scale the original video to a viewport of eight characters, a Python program was used to turn every frame of the scaled video into code to generate the custom bitmaps for each chunk of the viewport. Even with the low refresh rate of the display and the shrunken frame size, the result is a recognizable video, helped no doubt by the choice of the shadow-puppet Bad Apple!! video. Check it out after the break to see how it looks.

We saw a similar rendering of the same video on LCD a while back; that effort was amazing in that it was an EEPROM-only implementation, along with a somewhat bigger LCD with better contrast. That project served as inspiration for [arduinocelantano]’s build here, which in some ways we think looks a bit better — perhaps it’s the inverted pixels. Either way, hats off to both builders for pushing past the normal constraints and teaching us something interesting.

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The Little 3D-Printed Tugboat That Could

June 14, 2022 by 24 Comments

If you’ve ever spent time watching the goings-on at a seaport, you must have seen tugboats at work: those little boats that push, pull and nudge enormous cargo ships through tight corners in the harbor. They manage to do that thanks to hugely powerful engines sitting inside their relatively small hulls; their power-to-tonnage ratio can be ten times that of most commercial ships.

One hardware hacker who enjoys building similarly-overpowered machinery is [Luis Marx], and it might not come as a surprise that his latest project is an actual tugboat. Living on the shores of Lake Constance in southern Germany, [Luis] likes to spend time on the water, but got fed up with the chore of paddling. Local regulations restrict the use of outboard motors but allow the use of R/C model boats; therefore, building an R/C tugboat to move yourself around the lake should be perfectly legal.

While we’re not sure if the Lake Constance Police will follow the same reasoning, [Luis]’s model tugboat is a wonderful piece of engineering. With a design inspired by 3DBenchy, the standard 3D printer benchmark that probably anyone with a 3D printer has printed at some point, it took about 30 hours to create the parts plus a generous helping of epoxy resin to make it all waterproof. A beefy lithium-ion battery pack drives two brush-less DC motors designed for racing drones, which together can put out nearly one kilowatt of power.

That, unfortunately, turned out to be way more than the little boat could handle: any attempt at using it simply caused it to leap out of the water and land on its back. Setting the motor controller to around 50% made it much more controllable, yet still strong enough to move [Luis] around on his standup paddle board. The boat is controlled through a custom-made handheld R/C controller that communicates with the ESP8266 inside the boat through WiFi. With no rudder, left-right control is effected by simply reducing the power of one motor by half.

A fully-charged battery pack provides enough juice for about 40 minutes of tugging, so it’s probably a good idea to bring along paddles in any case. Unless, of course, you’ve also got a solar-powered autonomous tugboat ready to come to your rescue.

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Raspberry Pi Pico Replaces PlayStation Memory Card

June 13, 2022 by 16 Comments

It’s almost hard to believe these days, what with modern game consoles packing terabytes of internal storage, but there was a time when the totality of your gaming career would be stored on an external memory card that held just a few megabytes of save data. Of course, before that you had to write down a sequence of random letters and numbers to pick up where you left off, but that’s a story for another day.

While the memory card concept might be quaint to the modern gamer, its modular nature does provide the hacker with some interesting avenues to explore. For example, take a look at the very impressive PicoMemcard project from [Daniele Giuliani]. Hardware wise, it doesn’t get much simpler than this. You just take the PCB from a cheap (or dead) PlayStation memory card, and solder seven jumpers to the edge connector contacts so you can plug them into the Pico. Then you’ve just got to upload the firmware to the Pico, and you’re done. Continue reading “Raspberry Pi Pico Replaces PlayStation Memory Card” →

Another Rubik’s Cube Robot Is Simple But Slow

June 13, 2022 by 5 Comments

[AndreaFavero] says that the CuboTino emphasizes simplicity and cost-savings over speed. However, solving the puzzle in about 90 seconds is still better than we can do. The plucky solver uses a Pi and a camera to understand what the cube looks like and then runs it through a solver to determine how to move.

Watching the video below, we were impressed with the mechanics. The titled surface solves a few problems and makes manipulation easier. The way the mechanics are arranged, it only takes a pair of servos to flip the cube around as you like. Continue reading “Another Rubik’s Cube Robot Is Simple But Slow” →

Helium Recovery System Saves Costs

June 13, 2022 by 31 Comments

Helium is the most common element in the universe besides hydrogen, but despite this universal abundance it is surprisingly difficult to come across on Earth. Part of the problem is that it is non-renewable, so unless it is specifically captured during mining its low density means that it simply escapes the atmosphere. For that reason [Meow] maintains a helium recovery system for a lab which is detailed in this build.

The purpose of the system is to supply a refrigerant to other projects in the lab. Liquid helium is around 4 Kelvin and is useful across a wide variety of lab tests, but it is extremely expensive to come across. [Meow]’s recovery system is given gaseous helium recovered from these tests, and the equipment turns it back into extremely cold liquid helium in a closed-cycle process. The post outlines the system as a whole plus goes over some troubleshooting that they recently had to do, and shows off a lot of the specialized tools needed as well.

Low-weight gasses like these can be particularly difficult to deal with as well because their small atomic size means they can escape fittings, plumbing, and equipment quite easily compared to other gasses. As a result, this equipment is very specialized and worth a look. For a less lab-based helium project, though, head on over to this helium-filled guitar instead.