Sounding The Humble LED

February 27, 2021 by Kerry Scharfglass 22 Comments

Here at Hackaday we’re no strangers to the colorful glow of LEDs. But what if there was more to appreciate beneath the surface? Back in 2011 [Windell] over at Evil Mad Scientist dug into a certain variety of LED and discovered they had a song to sing.

Over the last couple decades, you’ve likely encountered the flickering “candle flame” variety of LED. Often found embedded in small plastic candle simulacra they are shaped like typical through hole “gumdrop” style LEDs, but pack some extra magic which causes them to flicker erratically. Coupled with a warm white color temperature the effect isn’t entirely dissimilar to the flickering of a candle flame.

To the Hackaday reader (and [Windell]) the cause of the flickering may be fairly clear, there is an IC embedded in the lens of the LED. See photo at top for an example of how this might look, helpfully magnified by the lens of the LED itself. Looking through the lens the captive die is visible, as well as the bond wires connecting it to the legs and light emitting diode itself. [Windell]’s observation is that together this assembly makes for a somewhat strange electrical component; from the perspective of the circuit it appears to randomly vary the current flowing through the LED.

He includes two interesting demos. One is that by attaching the flickering LED to a BJT he can turn it into a current amplifier and successfully drive a much more powerful 1W LED with the same effect. The other is that with the power of the amplifier the same flickering LED can drive a buzzer as well. The effect is surprisingly pleasant, though we’d hesitate to call it musical.

For a more recent example of a similar phenomenon with a very different sound, check out out [Emily Velasco]’s playback of a similarly constructed RGB color changing LED, embedded below. We’ve seen optical tools used to decode LED flickers into data streams, but not for audio playback! We have also covered some LED flicker reverse engineering that spills more of the mystery sealed up in these specialized diodes.

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We Bet You’ve Never Seen A Pink Denture Synth

December 21, 2020 by Lewin Day 18 Comments

At one end of the synthesizer world, there stands commercial instruments designed for the ultimate in sound quality and performance, tailored to the needs of professional musicians. On the other, there are weird, wacky prototypes and artistic builds that aim to challenge our conception of what a synth should be. The VOC-25 by [Love Hultén] falls firmly in the latter category.

The synth is built around the Axoloti Core, a microcontroller board set up for audio experimentation. Packing stereo DACs and ADCs, and MIDI input and output, it’s the perfect base for such a project. Loaded up with vocal samples, it’s played by a keyboard in a fairly typical sense. Where things get interesting is the panel containing 25 sets of plastic teeth. The teeth open and close when the user plays the corresponding note, thanks to a solenoid. Along with the clacking sound of the machinery and pearly whites themselves, it adds quite a creepy vibe to the piece.

With its clean pastel enclosure, we can imagine this piece as the star of an avant-garde filmclip, or merely something to terrify children at a Maker Faire. It’s a fun build, to be sure. We’ve seen some other great experimental synths over the years, too – this 48 Game Boy build comes to mind. Video after the break.

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Remoticon Video: Intro To Modern Synthesis Using VCV Rack

December 15, 2020 by Dan Maloney 10 Comments

Modular synthesizers, with their profusion of knobs and switches and their seemingly insatiable appetite for patch cables, are wonderful examples of over-complexity — the best kind of complexity, in our view. Play with a synthesizer long enough and you start thinking that any kind of sound is possible, limited only by your imagination in hooking up the various oscillators, filters, and envelope generators. And the aforementioned patch cables, of course, which are always in short supply.

Luckily, though, patch cables and the modules they connect can be virtualized, and in his 2020 Remoticon workshop, Jonathan Foote showed us all the ways VCV Rack can emulate modular synthesizers right on your computer’s desktop. The workshop focused on VCV Rack, where Eurorack-style synthesizer modules are graphically presented in a configurable rack and patched together just like physical synth modules would be.

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He’s The Operator Of His Pocket Arduino

November 27, 2020 by Bryan Cockfield 6 Comments

The band Kraftwerk hit the music scene with its unique electronic sound in the 70s in Germany, opening the door for the electronic music revolution of the following decade. If you’re not familiar with the band, they often had songs with a technology theme as well, and thanks to modern microcontroller technology it’s possible to replicate the Kraftwerk sound with microcontrollers as [Steven] aka [Marquis de Geek] demonstrates in his melodic build.

While the music is played on a Stylophone and a Korg synthesizer, it is fed through five separate Arduinos, four of which have various synths and looping samplers installed on them (and presumably represent each of the four members of Kraftwerk). Samplers like this allow pieces of music to be repeated continuously once recorded, which means that [Steven] can play entire songs on his own. The fifth Arduino functions as a controller, handling MIDI and pattern sequencing over I2C, and everything is finally channeled through a homemade mixer.

[Marquis] also dressed in Kraftwerk-appropriate attire for the video demonstration below, which really sells the tribute to the famous and groundbreaking band. While it’s a great build in its own right and is a great recreation of the Kraftwerk sound, we can think of one more way to really put this project over the top — a Kraftwerk-inspired LED tie.

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3D Print Your Way To A Modular MIDI Playset

November 16, 2020 by Tom Nardi 6 Comments

Have you ever wanted to experiment with MIDI, but didn’t know where to start? Or perhaps you didn’t think you could afford to properly outfit your digital beat laboratory, especially given the average hacker’s penchant for blinkenlights? Well worry no more, as [Johan von Konow] has unveiled a collection of DIY MIDI devices that anyone with a 3D printer can build on the cheap.

The LEET modular synthesizer is made up of a keyboard, drum pad, chord keyboard, arpeggiator and a step sequencer that plug into your computer and interface with industry standard digital audio workstation (DAW) programs. The down side is that they don’t do anything on their own, but this simplification allowed [Johan] to really streamline the design and bring the cost of the build down to the bare minimum.

Integrated wire channels mean no PCB is required.

You don’t need to build all the components either, especially if you’re just testing the waters. The keyboard is a great starting point, and even if you have to buy all the components new from eBay, [Johan] says it shouldn’t cost you more than $10 USD to build. You just need an Arduino Pro Micro, some tact switches, and a section of WS2812 RGB LED strip. There’s an excellent chance you’ve already got some of that in the parts bin, which will make it even cheaper.

There is one missing element though: the PCB. But not because you have to source it yourself. Like his clever Arduboy clone we covered earlier in the year, the 3D printed bodies for all of the LEET devices have integrated wiring channels that serve as a stand-in for a traditional circuit board. Simply place all your components, push some stiff 0.3 mm diameter wire down into the channels, and solder the ends. It’s a very neat approach, and something we could see becoming more popular as desktop 3D printers become an increasingly common sight in the home workshop.

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Adding MIDI To A Mini Synth Is Easy As Pi

September 21, 2020 by Kristina Panos 11 Comments

There are a handful of relatively dirt cheap synths out there like the KORG Monotron, but many of them use ribbon controllers that aren’t very precise. Ribbon controllers basically slide pots that you operate with your finger or a stylus. They’re painted to look like piano keys in order to show you approximately where the notes are supposed to be. The Stylophone is another extremely affordable synth that does even less as a synthesizer and uses this type of input. It’s a fun input if you don’t mind imprecision, but can be annoying otherwise.

[schollz] isn’t satisfied to synth this way, so they added MIDI input to their KORG Monotron using a Raspberry Pi and a DAC. Fortunately, the Monotron is quite the hackable little synth, with nice, big, labelled pads on the PCB.

All it really took was a couple of solder joints in the right places, plus a clever Python script. The script listens for MIDI input from a keyboard, and then controls an MCP4725 DAC, which sends voltages to the Monotron. [schollz] wrote a tuning function that computes the FFT of the MIDI tones to find the fundamental frequencies of each to send along to the Monotron. Check it out after the break.

If liquid control is what you’re after but all you have is a keyboard, try making your own ribbon controller.

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Mini Marble-Powered Synth Pays Homage To Its Bigger Cousins

August 22, 2020 by Dan Maloney 8 Comments

If imitation is the sincerest form of flattery, what then are we to make of something that shares only a few of the original’s design elements, operates in a completely different way, and has been scaled down to a fifth its size? Still seems like flattery to us.

Despite the changes, it’s clear where [Love Hultén] took inspiration for his miniature Marble Machine XS. Readers will no doubt see in it elements from [Martin Molin]’s original Marble Machine, the fantastic plywood and Lego musical contraption, along with his new Marble Machine X, the construction of which never seems to end. Like the originals, [Love]’s miniature version uses a lot of steel balls, albeit considerably scaled down, and it still uses a programming drum to determine where and when to drop them. But rather than strike real traditional instruments, the falling balls strike synthesizer keys, triggering a range of sounds through its built-in speaker. The whole thing is powered by a small electric motor rather than being hand-cranked and is small enough to sit on a desktop, a decided advantage over the mammoth machines to which it pays homage.

We have to say that as much as we love the hacksmanship of the original Marble Machine and the craftsmanship of its successor, the look and feel of [Love]’s machine just blows us away. We’re not sure what materials he used, but the whole hammertone paint scheme and Meccano look is a feast for nostalgic eyes.

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