organ

38 Articles

Tonewheels Warble In This Organ-Inspired Musical Instrument

February 10, 2021 by 9 Comments

Younger readers may not recall the days when every mall had a music store — not the kind where tapes and LPs were sold, but the kind where you could buy instruments. These places inevitably had an employee belting out mall-music to all and sundry on an electric organ. And more often than not, the organist was playing a Hammond organ, with the distinct sound of these instruments generated by something similar to this tonewheel organ robot.

Tonewheels are toothed ferromagnetic wheels that are rotated near a pickup coil. This induces a current that can be amplified; alter the tooth profile or change the speed of rotation, and you’ve got control over the sounds produced. While a Hammond organ uses this technique to produce a wide range of sounds, [The Mixed Signal]’s effort is considerably more modest but nonetheless interesting. A stepper motor and a 1:8 ratio 3D-printed gearbox power a pair of shafts which each carry three different tonewheels. The tonewheels themselves are laser-cut from mild steel and range from what look like spur gears to wheels with but a few large lobes. This is a step up from the previous version of this instrument, which used tonewheels 3D-printed from magnetic filament.

Each tonewheel has its own pickup, wound using a coil winder that [TheMixed Signal] previously built. Each coil has a soft iron core, allowing for the addition of one or more neodymium bias magnets, which dramatically alters the tone. The video below shows the build and a demo; skip ahead to 16:10 or so if you just want to hear the instrument play. It’s — interesting. But it’s clearly a work in progress, and we’re eager to see where it goes. Continue reading “Tonewheels Warble In This Organ-Inspired Musical Instrument” →

Wurlitzer Note Visualizer Gets A 2020-Spec Replica

June 20, 2020 by 1 Comment

Way back in the 1970s, when smog laws were choking American V8s and the oil crisis was in full swing, Wurlitzer released their Key Note Visualizer. Intended as a teaching aid, the device lit up keys on a keyboard graphic, allowing an organ player to visually demonstrate their performance to a class. [Guy Dupont] set out to replicate this hardware, but with a modern twist.

The build consists of an ESP-32, which accepts MIDI data over Bluetooth Low Energy. This is then used to light up a series of RGB LEDs on a musical staff and a keyboard graphic, corresponding to the notes being played. The LEDs used are the old-school four-wire type, rather than more modern data-driven types. They’re placed in 3D-printed holders which serve to stop the light from each LED bleeding into adjacent areas. The faceplate is made of acrylic, stencilled with that classic orange paint and with vinyl decals applied for the markings. It’s all wrapped up in a walnut case, which [Guy] CNC machined himself.

It’s a tidy build that faithfully recreates the 1970s aesthetic of the original. We plaintively wish that manufacturers would release more electronics in walnut enclosures, though ask politely that they leave cheap veneer in the past where it belongs.

Of course, if you like your musical displays more abstract than instructional, try this giant oscilloscope visualisation on for size. Video after the break.

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Be Still, My Animatronic Heart

January 19, 2020 by 10 Comments

Fair warning for the squeamish: some versions of [Will Cogley]’s animatronic heart are realistic enough that you might not want to watch the video below. That’d be a shame though, because he really put a lot of effort into the build, and the results have a lot to teach about mimicking the movements of living things.

As for why one would need an animatronic heart, we’re not sure. [Will] mentions no specific use case for it, although we can think of a few. With the Day of Compulsory Romance fast approaching, the fabric-wrapped version would make a great gift for the one who stole your heart, while the silicone-enrobed one could be used as a movie prop or an awesome prank. Whatever the reason, [Will]’s build is a case study in incremental development. He started with a design using a single continuous-rotation servo, which powered four 3D-printed paddles from a common crank. The four paddles somewhat mimicked the movements of the four chambers of the heart, but the effect wasn’t quite convincing. The next design used two servos and complex parallelogram linkages to expand each side of the heart in turn. It was closer, but still not quite right.

After carefully watching footage of a beating heart, [Will] decided that his mechanism needed to imitate the rapid systolic contraction and slow diastolic expansion characteristic of a real heart. To achieve this, his final design has three servos plus an Arduino for motion control. Slipped into a detailed silicone jacket, the look is very realistic. Check out the video below if you dare.

We’ve seen plenty of animatronic body parts before, from eyes to hands to entire faces. This might be the first time we’ve seen an animatronic version of an internal organ, though.

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Additive, Multi-Voice Synth Preserves Sounds, Too

January 13, 2020 by 2 Comments

For his final project in [Bruce Land]’s microcontroller design class, [Mark] set out to make a decently-sized synth that sounds good. We think you’ll agree that he succeeded in spades. Don’t let those tiny buttons fool you, because it doesn’t sound like a toy.

Why does it sound so good? One of the reasons is that the instrument samples are made using additive synthesis, which essentially stacks harmonic overtones on top the fundamental frequency of each note. This allows synthesizers to better mimic the timbre of natural, acoustic sounds. For each note [Mark] plays, you’re hearing a blend of four frequencies constructed from lookup tables. These frequencies are shaped by an envelope function that improves the sound even further.

Between the sound and the features, this is quite an impressive synth. It can play polyphonically in piano, organ, or plucked string mode through a range of octaves. A PIC32 runs the synthesizer itself, and a pair of helper PIC32s can be used to record songs to be played over. So [Mark] could record point and counterpoint separately and play them back together, or use the helper PICs to fine-tune his three-part harmony. We’ve got this thing plugged in and waiting for you after the break.

If PICs aren’t what you normally choose, here’s an FPGA synth.

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A STM32 Tonewheel Organ Without A Single Tonewheel

December 5, 2019 by 7 Comments

The one thing you might be surprised not to find in [Laurent]’s beautiful tonewheel organ build is any tonewheels at all.

Tonewheels were an early way to produce electronic organ sounds: by spinning a toothed wheel at different frequencies and transcending the signal one way or another it was possible to synthesize quite an array of sounds. We like to imagine that they’re all still there in [Laruent]’s organ, albeit very tiny, but the truth is that they’re being synthesized entirely on an STM32 micro controller.

The build itself is beautiful and extremely professional looking. We were unaware that it was possible to buy keybeds for a custom synthesizer, but a model from FATAR sits at the center of the show. There’s a MIDI encoder board and a Nucleo development board inside, tied together with a custom PCB. The UI is an momentary encoder wheel and a display from Mikroelektronika.

You can see and hear this beautiful instrument in the video after the break.

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A Fleet Of Pressure Washers Powers This Interactive Public Fountain

November 11, 2018 by 15 Comments

Public art installations can be cool. Adding in audience interactivity bumps up the coolness factor a bit. Throw civic pride, dancing jets of water, music, and lights into the project, and you get this very cool pressure washer powered musical fountain.

The exhibit that [Niklas Roy] came up with is called Wasserorgel, or “water organ”, an apt name for the creation. Built as part of a celebration of industry in Germany, the display was built in the small town of Winnenden, home to Kärcher, a cleaning equipment company best known for their line of pressure washers in the distinctive yellow cases. Eight of the company’s electric pressure washers were featured in the Wasserorgel, which shot streams of water and played notes in response to passersby tickling the sturdy and waterproof 3D-printed keyboard. The show was managed by an Arduino with a MIDI shield, which controlled the pressure washers via solid state relays and even accepted input from an anemometer to shut down the show if it got too windy, lest the nearby [Frau Dimitrakudi] be dampened.

The video below shows how engaging the Wasserorgel was during its weeks-long run in the town market square; there’s also one in German with build details. And while we can’t recall seeing pressure washers in public art before, we do remember one being used as the basis of a DIY water-jet cutter.

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Ask Hackaday Answered: The Tale Of The Top-Octave Generator

August 22, 2018 by 57 Comments

We got a question from [DC Darsen], who apparently has a broken electronic organ from the mid-70s that needs a new top-octave generator. A top-octave generator is essentially an IC with twelve or thirteen logic counters or dividers on-board that produces an octave’s worth of notes for the cheesy organ in question, and then a string of divide-by-two logic counters divide these down to cover the rest of the keyboard. With the sound board making every pitch all the time, the keyboard is just a simple set of switches that let the sound through or not. Easy-peasy, as long as you have a working TOG.

I bravely, and/or naïvely, said that I could whip one up on an AVR-based Arduino, tried, and failed. The timing requirements were just too tight for the obvious approach, so I turned it over to the Hackaday community because I had this nagging feeling that surely someone could rise to the challenge.

The community delivered! Or, particularly, [Ag Primatic]. With a clever approach to the problem, some assembly language programming, and an optional Arduino crystalectomy, [AP]’s solution is rock-solid and glitch-free, and you could build one right now if you wanted to. We expect a proliferation of cheesy synth sounds will result. This is some tight code. Hat tip!

Squeezing Cycles Out of a Microcontroller

Let’s take a look at [AP]’s code. The approach that [AP] used is tremendously useful whenever you have a microcontroller that has to do many things at once, on a rigid schedule, and there’s not enough CPU time between the smallest time increments to do much. Maybe you’d like to control twelve servo motors with no glitching? Or drive many LEDs with binary code modulation instead of primitive pulse-width modulation? Then you’re going to want to read on.

There are two additional tricks that [AP] uses: one to fake cycles with a non-integer number of counts, and one to make the AVR’s ISR timing absolutely jitter-free. Finally, [Ag] ended up writing everything in AVR assembly language to make the timing work out, but was nice enough to also include a C listing. So if you’d like to get your feet wet with assembly, this is a good start.

In short, if you’re doing anything with hard timing requirements on limited microcontroller resources, especially an AVR, read on!

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