Elegant Drum Machine from Teensy

Playing the drums is pretty hard, especially for the uncoordinated. Doing four things at the same time, all while keeping an even tempo, isn’t reasonable for most of us. Rather than hiring a drummer for your band who is well versed in this art, though, you might opt instead to outsource this job to a machine instead. It’s cheaper and also less likely to result in spontaneous combustion.

This drum machine is actually a MIDI Euclidean sequencer. Euclidean rhythms are interesting in their own regard, but the basics are that a common denominator between two beats is found in order to automatically generate complicated beats. This particular unit is running on a Teensy 3.5 and consists of four RGB rotary encoders, an SSD1306 LCD, four momentary buttons, and four 16 LED Neopixel rings. Setting each of the dials increases the number of beats for that particular channel, and it can be configured for an almost limitless combination of beats and patterns.

To really get a feel of what’s going on here, it’s worth it to check out the video after the break. MIDI is also a fascinating standard, beyond the fact that it’s one of the few remaining standards created in the 80s that still enjoys active use, it can also be used to build all kinds of interesting instruments like one that whacks wine glasses with mallets or custom synthesizers.

Thanks to [baldpower] for the tip!

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Can You Build An Open Source Pocket Operator?

Toys are now musical instruments. Or we’ll just say musical instruments are now toys. You can probably ascribe this recent phenomenon to Frooty Loops or whatever software the kids are using these days, but the truth is that it’s never been easier to lay down a beat. Just press the buttons on a pocket-sized computer.

One of the best examples of the playification of musical instruments is Pocket Operators from Teenage Engineering. They’re remarkable pieces of hardware, and really just a custom segment LCD and a few buttons. They also sound great and you can play real music with them. It’s a game changer when it comes to enabling musicianship.

Of course, with any popular platform, there’s a need for an Open Source copy. That’s where [Chris]’ Teensy Beats Shield comes in. It’s a ‘shield’ of sorts for a Teensy microcontroller that adds buttons, knobs, and a display, turning this into a platform that uses the Teensy’s incredible audio system designer.

When it comes to the world of microcontrollers and audio processing, the Teensy is a champ. The Teensy Audio Library has polyphonic playback, recording, synthesis, analysis, and effects, along with multiple simultaneous inputs and outputs. If you’re building a tiny synth that can fit in your pocket, the Teensy is the way to go, and [Chris]’ Teensy Beats Shield does it all, with a minimal and useful user interface. You can check out a video of the Teensy Beats Shield below.

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Synthesizing Mother Nature’s Sounds Like You’ve Never Seen Before

We’ve all heard the range of sounds to be made electronically from mostly discrete components, but what [Kelly Heaton] has achieved with her many experiments is a whole other world, the world of nature to be exact. Her seemingly chaotic circuits create a nighttime symphony of frogs, crickets, and katydids, and a pleasant stroll through her Hackaday.io logs makes how she does it crystal clear and is surely as delightful as taking a nocturnal stroll through her Virginia countryside.

Homemade piezo buzzer with amplifierThe visual and aural sensations of the video below will surely tempt you further, but in case it doesn’t, here’s a taste. When Radio Shack went out of business, she lost her source of very specific piezo buzzers and so had to reverse engineers theirs to build her own, right down to making her own amplifiers on circular circuit boards and vacuum forming and laser cutting the housings. For the sounds, she starts out with a simple astable multivibrator circuit, demonstrating how to create asymmetry by changing capacitors, and then combining two of the circuits to get something which sounds just like a cricket. She then shows how to add katydids which enhance the nighttime symphony with percussive sounds much like a snare drum or hi-hat. It’s all tied together with her Mother Nature Board built up from a white noise generator, Schmitt trigger, and shift registers to turn on and off the different sound circuits, providing a more unpredictable and realistic nighttime soundscape. The video below shows the combined result, though she admits she’ll never really be finished. And be sure to check out even more photos and videos of her amazing work in the gallery on her Hackaday.io page.

For the more familiar range of sounds, though no less varied, check out our own [Elliot William’s] series, Logic Noise, where he takes us through an extensive exploration of a less Mother Naturely soundscape.

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Fail of the Week: How Not to Design an RF Signal Generator

We usually reserve the honor of Fail of the Week for one of us – someone laboring at the bench who just couldn’t get it together, or perhaps someone who came perilously close to winning a Darwin Award. We generally don’t highlight commercial products in FotW, but in the case of this substandard RF signal generator, we’ll make an exception.

We suppose the fail-badge could be pinned on [electronupdate] for this one in a way; after all, he did shell out $200 for the RF Explorer signal generator, which touts coverage from 24 MHz to 6 GHz. But in true lemons-to-lemonade fashion, the video below he provides us with a thorough analysis of the unit’s performance and a teardown of the unit.

The first step is a look at the signal with a spectrum analyzer, which was not encouraging. Were the unit generating a pure sine wave as it should, we wouldn’t see the forest of spikes indicating harmonics across the band. The oscilloscope isn’t much better; the waveform is closer to a square wave than a sine. Under the hood, he found a PIC microcontroller and a MAX2870 frequency synthesizer, but a conspicuous absence of any RF filtering components, which explains how the output got so crusty. Granted, $200 is not a lot to spend compared to what a lab-grade signal generator with such a wide frequency range would cost. And sure, external filters could help. But for $200, it seems reasonable to expect at least some filtering.

We applaud [electronupdate] for taking one for the team here and providing some valuable tips on RF design dos and don’ts. We’re used to seeing him do teardowns of components, like this peek inside surface-mount inductors, but we like thoughtful reviews like this too.

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OTTO: A Pi Based Open Source Music Production Box

Want an open source portable synth workstation that won’t break the bank? Check out OTTO. [Topisani] started OTTO as a clone of the well-known Teenage Engineering OP-1. However, soon [Topisani] decided to branch away from simply cloning the OP-1 — instead, they’re taking a lot of inspiration from it in terms of form factor, but the UI will eventually be quite different.

On the hardware side, the heart of the OTTO is a Raspberry Pi 3. The all-important audio interface is a Fe-Pi Audio Z V2, though a USB interface can be used. The 48 switches and four rotary encoders are wrangled by a pair of Arduino pro micros which pass the data on to the Pi. Data is related to the user through a 320×200 LCD.

The software is being written from scratch in C++17. If you’re not a hardcore C++ developer, don’t worry. The synth engines, audio effects, and other DSP software is written in Faust, which is a bit easier to learn.

OTTO is actively being developed, with synth engines already running, a prototype in progress, and fleshed out guidelines for programming the UI. If you’re into creating music, this one is worth checking out, as is Zynthian, another Raspberry Pi based synth.

Shell Script Synthesizer Knocks Your SoX Off

Sound eXchange, or SoX, the “Swiss Army knife of audio manipulation” has been around for as long as the Linux kernel, and in case you’re not familiar with it, is a command line tool to play, record, edit, generate, and process audio files. [porkostomus] was especially interested about the generating part, and wrote a little shell script that utilizes SoX’s built-in synthesizer to compose 8-bit style music.

The script comes with a simple yet straightforward user interface to record the lead and bass parts into a text file, and play them back later on. Notes from C2 to C5 are currently supported, and are mapped to the keyboard in a two-row piano layout. The output file format itself is just a plain text listing of the played note, wave form, and note length. This lets you easily edit the song or even generate it from an alternative source, for example MIDI. Also note that there are no initial audio files required here, SoX will generate them as needed.

Admittedly, the command line interface may not be the most convenient way to create music, but nevertheless, it is a way — and that is [porkostomus]’s main mission here. Also, SoX is fun — and versatile, you can apply its audio effects even on images, or decode strange signals sent from a helicopter with it.

A Fully Open Source Raspberry Pi Synthesizer

Have you ever seen something and instantly knew it was something you wanted, even though you weren’t aware it existed a few seconds ago? That’s how we felt when we received a tip about Zynthian, a fully open source (hardware and software) synthesizer. You can buy the kit online directly from the developers, or build your own from scratch using their documentation and source code. With a multitude of filters, effects, engines, and essentially unlimited upgrade potential, they’re calling it a “Swiss Army Knife of Synthesis”. We’re inclined to agree.

At the most basic level, the Zynthian is a Raspberry Pi 3 with a touch screen, a few rotary encoders, a dedicated sound card, and MIDI support. Software wise the biggest feature is arguably the real-time Linux kernel for the lowest latency possible. There’s also a custom web interface so you can control the Zynthian from another machine on the network if you want. As a matter of course, it also includes a wide array of pre-installed audio packages to experiment and create with.

Kits are offered at various prices from $420 USD for the top of the line model down to unpopulated PCBs for a few bucks. We like that they broke things down this way; allowing users of various skill (and or patience) to pay what they want. If you just want to buy the custom boards and roll your own case and Pi solution, you can do that.

If you want to go all in, you can build one entirely from scratch as well. Everything from the CAD files for the case to their custom rotary encoder library is completely open (most licensed under GPL v3) for anyone to use however they see fit. There’s even a page in the wiki for listing hardware which isn’t officially supported by the project, but remain as options for those looking to cut their own path.

Synthesizers are a fairly popular hacker project, from Google’s AI-powered version to single chip exercises in frugality. If you want to learn even more about the fine line between digital noise and music, check out this fantastic series by our very own [Elliot Williams].

[Thanks to Mynasru for the tip.]

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