Raspberry Pi Creates Melody

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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Laser Theremin Turns Your Hand Swooshes Into Music

In a world where smartphones have commoditized precision MEMS Sensors, the stage is set to reimagine clusters of these sensors as something totally different. That’s exactly what [chronopoulos] did, taking four proximity sensors and turning them into a custom gesture input sensor for sound generation. The result is Quadrant, a repurposable human-interface device that proves to be well-posed at detecting hand gestures and turning them into music.

At its core, Quadrant is a human interface device built around an STM32F0 and four VL6180X time-of-flight proximity sensors. The idea is to stream the measured distance data over as fast as possible from the device side and then transform it into musical interactions on the PC side. Computing distance takes some time, though, so [chronopoulos] does a pipelined read of the array to stream the data into the PC over USB at a respectable 30 Hz.

With the data collected on the PC side, there’s a spread of interactions that are possible. Want a laser harp? No problem, as [chronopoulos] shows how you can “pluck” the virtual strings. How about an orientation sensor? Simply spread your hand over the array and change the angle. Finally, four sensors will also let you detect sweeping gestures that pass over the array, like the swoosh of your hand from one side to the other. To get a sense of these interactions, jump to the video demos at the 2:15 mark after the break.

If you’re curious to dig into the project’s inner workings, [chronopoulos] has kindly put the firmware, schematics, and layout files on Github with a generous MIT License. He’s even released a companion paper [PDF] that details the math behind detecting these gestures. And finally, if you just want to cut to the chase and make music of your own, you can actually snag this one on Tindie too.

MEMs sensors are living a great second life outside our phones these days, and this project is another testament to the richness they offer for new project ideas. For more MEMs-sensor-based projects, have a look at this self-balancing robot and magic wand.

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Hackaday Links: September 26, 2021

Dealing with breakdowns is certainly nothing new for drivers; plenty of us have had our ride die in mid-flight, and experienced the tense moment when it happens in traffic. But the highly integrated and instrumented nature of the newest generation of electric vehicles can bring an interesting twist to the roadside breakdown, if the after-action report of a Tesla driver is any indication.

While driving on a busy road at night, driver [Pooch] reports that his Tesla Model S started beeping and flashing warnings to get to the side of the road right away. [Pooch] tried to do so, but the car died, coasted to a stop in the middle of the road, and engaged the parking brakes. The bricked Tesla would have been a sitting duck in the middle of the road but for a DOT crew who happened to be nearby and offered to provide some protection while [Pooch] waited for help. The disturbing part was the inability to get the car into any of the service modes that might let it be pushed off to the shoulder rather than stuck in traffic, something that’s trivial to do in ICE vehicles, at least older ones.

In other electric vehicle news, Chevy Bolt owners are turning into the pariahs of the parking garage. General Motors is telling Bolt EV and EUV owners that due to the risk of a battery fire, they should park at least 50 feet (15 meters) away from other vehicles, and on the top level of any parking structures. There have been reports of twelve battery fires in Bolts in the US recently, which GM says may be due to a pair of manufacturing defects in the battery packs that sometimes occur together. GM is organizing a recall to replace the modules, but isn’t yet confident that the battery supplier won’t just be replicating the manufacturing problem. The social distancing rules that GM issued go along with some fairly stringent guidelines for charging the vehicle, including not charging overnight while parked indoors. With winter coming on in the northern hemisphere, that’s going to cause a bit of inconvenience and probably more than a few cases of non-compliance that could end in tragedy.

Fans of electronic music might want to check out “Sisters with Transistors”, a documentary film about some of the pioneering women of electronic music. Electronic music has been around a lot longer than most of us realize, and the film reaches back to the 1920s with Theremin virtuoso Clara Rockmore, and continues on into the 1980s with Laurie Spiegel, whose synthesizer work has been speeding away from Earth for the last 44 years on the Golden Records aboard the Voyager spacecraft. Hackaday readers will no doubt recognize some of the other women featured, like Daphne Oram and Delia Derbyshire, who cobbled together the early Dr. Who music with signal generators, tape loops, and random bits of electronics in the pre-synthesizer days of the early 60s. We’ve watched the trailer for the film and it looks pretty good — just the kind of documentary we like.

We’re big fans of circuit sculpture around here, and desperately wish we had the patience and the skill to make something like Mohit Bhoite or Jiri Praus can make. Luckily, there’s now a bit of a shortcut — Geeek Club’s Cyber Punk PCB Construction Kit. These kits are a little like the love child of Lego and PCBWay, with pieces etched and cut from PCB stock. You punch the pieces out, clean up the mouse bites, put Tab A into Slot B, and solder to make the connection permanent. Each kit has some components for the requisite blinkenlight features, which add to the cool designs. Looks like a fun way to get someone started on soldering, or to build your own skills.

And finally, another nail was driven into the coffin of Daylight Savings Time this week, as the island nation of Samoa announced they wouldn’t be “springing ahead” as scheduled this weekend. Daylight Savings Time has become a bone of contention around the world lately, and mounting research shows that the twice-yearly clock changes cause more trouble than they may be worth. In Europe, it’s due to be banned as soon as all the member nations can agree on normal time or summer time.

In the case of Samoa, DST was put into effect in 2010 on the assumption that it would give plantation workers more productive hours in the field and save energy. Instead, the government found that the time change just gave people an excuse to socialize more, which apparently upset them enough to change the rule. So there you have it — if you don’t like Daylight Savings Time, start partying it up.

Optical Theremin Makes Eerie Audio With Few Parts

[Fearless Night]’s optical theremin project takes advantage of the kind of highly-integrated parts that are available to the modern hacker and hobbyist in all the right ways. The result is a compact instrument with software that can be modified using the Arduino IDE to take it places the original Theremin design could never go.

The design is based on a ‘Blue Pill’ STM32 MCU development board and two Avago APDS-9960 gesture sensor breakout boards, along with a few other supporting components. Where the original Theremin sensed hand proximity using two antenna-like capacitive sensors to control note frequency and volume, this design relies on two optical sensors to do the same job.

[Fearless Night] provides downloads for the schematic, code, parts list, and even 3D models for the enclosure. PCB files are also included for a convenient assembly, but since the component count is fairly low, a patient hacker should be able to get away with soldering it up by hand without much trouble.

This project creates the audio using the STM32’s Direct Digital Synthesis (DDS) capability and a simple low-pass filter, and has several ways to fine-tune the output. What’s DDS? Our own Elliot Williams explains it in terms of audio output for microcontrollers, and if you’d like a more comprehensive overview, Bil Herd will happily tell you all about it.

Co41D 2020 MIDI Theremin Sounds Pretty Sick

As the pandemic rages on, so does the desire to spend the idle hours tinkering. [knaylor1] spent the second UK lockdown making a sweet Theremin-inspired noise machine with a low parts count that looks like a ton of fun.

It works like this: either shine some light on the photocells, cover them up, or find some middle ground between the two. No matter what you do, you’re going to get cool sounds out of this thing.

The photocells behave like potentiometers that are set up in a voltage divider. An Arduino UNO takes readings in from the photocells, does some MIDI math, and sends the serial data to a program called Hairless MIDI, which in turn sends it to Ableton live.

[knaylor1] is using a plugin called TAL Noisemaker on top of that to produce the dulcet acid house tones that you can hear in the video after the break.

If you’ve never played with light-dependent resistors before, do yourself a favor and spend a little bit of that Christmas cash on a variety pack of these things. You don’t even need an Arduino to make noise, you can use them as the pots in an Atari Punk console or make farty square waves with a hex inverting oscillator chip like the CD40106. Our own [Elliot Williams] once devoted an entire column to making chiptunes.

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Clara Rockmore. Photo by Renato Toppo, © The Nadia Reisenberg / Clara Rockmore Foundation

The Theremin Is 100 Years Old; Celebrating The Spookiest Of Instruments

It wouldn’t be October without Halloween, and it wouldn’t be Halloween without some spooky music. There’s no instrument spookier than a Theremin, which also happens to be one of the world’s first electronic instruments.

Leon Theremin plays his namesake instrument. Image via Linda Hall Library

You’ve no doubt heard the eerie, otherworldly tones of the Theremin in various 1950s sci-fi films, or heard the instrument’s one-of-a-kind cousin, the Electro-Theremin in “Good Vibrations” by the Beach Boys. The Theremin turns 100 years old this month, so we thought we’d take a look at this strange instrument.

One hundred years ago, a young Russian physicist named Lev Sergeyevich Termen, better known as Leon Theremin, was trying to invent a device to measure the density of various gases. In addition to the standard analog needle readout, he wanted another way to indicate the density, so he devised an oscillator whistle that would change pitch based on the density.

He discovered by accident that having his hand in the field of the antenna changed the pitch of the whistle, too. Then he did what any of us would do — played around until he made a melody, then called everyone else in the lab over to check it out.

Theremin soon showed his device to Lenin, who loved it so much that he sent Lev on a world tour to show it off. While in New York, he played it for Rachmaninoff and Toscanini. In fact you can see a video recording of Leon playing the instrument, a performance that’s more hauntingly beautiful than spooky. In 1928, he patented the Theremin in the United States and worked with RCA to produce them.

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Hackaday Podcast 026: Tamper-Proof Electronics, Selfie Drones, Rocket Fuel, Wire Benders, And Wizard-Level Soldering

Hackaday Editors Mike Szczys and Elliot Williams are back after last week’s holiday break to track down all of the hacks you missed. There are some doozies; a selfie-drone controlled by your body position, a Theremin that sings better than you can, how about a BGA hand-soldering project whose creator can’t even believe he pulled it off. Kristina wrote a spectacular article on the life and career of Mary Sherman Morgan, and Tom tears down a payment terminal he picked up in an abandoned Toys R Us, plus much more!

Take a look at the links below if you want to follow along, and as always tell us what you think about this episode in the comments!

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

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