Cigar Box Synth Is A Fun Time

June 13, 2018 by Lewin Day 4 Comments

It’s fair to say that the groovebox market has exploded. Store shelves are overflowing with the umpteenth releases from KORG’s Volca line and the latest Pocket Operators. These devices often feature a wide array of tones in an enticingly compact and attractive package, but is it possible to build something similar at home? As [lonesoulsurfer] relates, it certainly is.

The Cigar Box Synth is, well… a synth, built in a cigar box. Based upon a 555 & 556 timer, and a 4017 decade counter, it provides a wealth of beepy goodness all crammed into a neat wooden package. We dig the cigar box form factor, as it’s a readily available wooden box often finished in an attractive way, and readily reworkable for all kinds of projects.

Sound is controlled with three master potentiometers, and there are four separate potentiometers to set the note for each of the four steps in the sequence. While its melodic abilities are limited to just four notes, it’s certainly something fun to play with and can act as a great jumping off point for further electronic experimentation in this area.

It takes us back to our guide on building DIY logic-based synthesizers – read on!

Framed Raspberry Pi Keeps Tabs On Spotify

June 9, 2018 by Tom Nardi 8 Comments

Perhaps you’ve noticed, but we here at Hackaday have a slight obsession with the over-engineered. One could fairly say there’s a linear relationship between how likely we are to feature a project and how needlessly complex it is. That said, it isn’t as if we are unable to appreciate a minimalist approach. Taking the scenic route can be a lot of fun, but sometimes it’s nice to just get where you’re going before you run out of gas.

This very slick Spotify “Now Playing” display created by [Jon Ashcroft] is a perfect example of that principle. The hardware is so straightforward that it’s barely worth mentioning: a Raspberry Pi with a small HDMI display, tucked neatly into a photo frame. Nothing to get too excited about there. The real hook with this particular project is the software.

[Jon] is a web developer by trade, so it’s natural he would approach his personal projects with that same mentality. Rather than one of the “usual suspects” for a Pi project like Python, he wrote his software in ES6; which the Pi is running through Chromium in kiosk mode (full screen web content, no top bar). For those of you who aren’t keeping up on web languages, ES6 is short for EcmaScript 6: a new version of the standard on which JavaScript is based. It’s a bit heavier on resources than is strictly necessary, but it works well enough in the end.

Using Spotify’s excellent API, his software pulls down the current track information and stores it locally. It does this every ~4 seconds, checking to see if the track has changed. [Jon] isn’t thrilled with this brute force method, but it works for now. It displays the current playing song and artist, and uses a library called node-vibrant to extract a dominant color from the album art and use that to create a complementary background color. Very slick.

[Jon] provides all of his source code and made it easy to connect to your own Spotify account, so don’t be surprised if you see this running on a “Magic Mirror” near you soon.

Monotron Gets All The Mods

June 9, 2018 by Adam Fabio 3 Comments

[Harry Axten] turned the diminutive Korg Monotron into a playable analog synthesizer, complete with a full-sized keyboard spanning two octaves and a MIDI interface.

Korg Introduced the Monotron analog mini-synthesizer back in 2010. They also dropped the schematics for the synth. Hackers wasted no time modifying and improving the Monotron. [Harry] incorporated several of these changes into his build. The Low-Frequency Oscillator (LFO) has been changed over to an envelope generator. The ribbon controller is gone, replaced with a CV/gate interface to sound notes.

The CV/gate interface, in turn, is connected to an ATMega328P which converts it to MIDI. MIDI data comes from one of two sources: A two-octave full-sized keyboard pulled from a scrapped MIDI controller or a MIDI connector at the back.

The user interface doesn’t stop with the keyboard. The low-cost pots on the original Monotron have been replaced with much higher quality parts on the front panel. The tuning pot is a 10-turn device, which allows for precision tuning. All the mods are mounted on a single board, which is connected to the original Monotron board.

The fruit of all hard work is an instrument that is a heck of a lot of fun to play. Check it out in the video below. Want more? You can read all about hacking about the Monotron’s bigger brother, the Monotribe.

Continue reading “Monotron Gets All The Mods” →

A Fully Open Source Raspberry Pi Synthesizer

June 8, 2018 by Tom Nardi 19 Comments

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.]

Continue reading “A Fully Open Source Raspberry Pi Synthesizer” →

The random logic section implmented using I2L

Space Invaders Sound Chip Went Old School With I2L

June 8, 2018 by Steven Dufresne 6 Comments

It must be everyone’s birthday today because [Ken Shirriff] has come out with a gift for us. He’s done another pass at reverse engineering the 76477 Space Invaders sound chip from the 1970s and found it’s full of integrated injection logic (I²L), making it a double treat: we get to explore the more of this chip which made sounds for so many of our favorite games, and we explore a type of logic which was to be the successor to TTL until CMOS came along.

This article has a similar shape to his last one, first introducing I²L, followed by showing us what it looks like on the die, and then covering the different functional elements which make heavy use of it. The first of these is the noise generator made up of a section of shift registers and a ring oscillator. That’s followed by a noise filter which doesn’t use I²L but does use current mirrors. And lastly, he talks about the mixer which mixes output from the noise generator and elements covered in his previous article, the voltage-controlled oscillator, and the super-low frequency oscillator. Oddly enough, and as he points out, it isn’t an analog mixer. Instead, it just ANDs together the various inputs.

[Ken’s] no stranger to putting dies under the microscope. Check out our coverage of his talk at the 2016 Hackaday SuperConference where he shows us the guts of such favorites as the Z80 and the 555 timer IC.

Facebook’s Universal Music Translator

June 2, 2018 by Steven Dufresne 20 Comments

Star Trek has its universal language translator and now researchers from Facebook Artificial Intelligence Research (FAIR) has developed a universal music translator. Much of it is based on Google’s WaveNet, a version of which was also used in the recently announced Google Duplex AI.

The inspiration for it came from the human ability to hear music played by any instrument and to then be able to whistle or hum it, thereby translating it from one instrument to another. This is something computers have had trouble doing well, until now. The researchers fed their translator a string quartet playing Haydn and had it translate the music to a chorus and orchestra singing and playing in the style of Bach. They’ve even fed it someone whistling the theme from Indiana Jones and had it translate the tune to a symphony in the style of Mozart.

Shown here is the architecture of their network. Note that all the different music is fed into the same encoder network but each instrument which that music can be translated into has its own decoder network. It was implemented in PyTorch and trained using eight Tesla V100 GPUs over a total of six days. Efforts were made during training to ensure that the encoder extracted high-level semantic features from the music fed into it rather than just memorizing the music. More details can be found in their paper.

So if you want to hear how an electric guitar played in the style of Metallica might have been translated to the piano by Beethoven then listen to the samples in the video below.

Continue reading “Facebook’s Universal Music Translator” →

Bike Helmet Plays Music Via Tiny Motors For Bone Conduction

June 2, 2018 by Donald Papp 20 Comments

[Matlek] had an interesting problem. On one hand, a 40 minute bike commute without music is a dull event but in France it is illegal for any driver to wear headphones. What to do? Wanting neither to break the law nor accept the risk of blocking out surrounding sounds by wearing headphones anyway, and unwilling to create noise pollution for others with a speaker system, [Matlek] decided to improvise a custom attachment for a bike helmet that plays audio via bone conduction. We’ll admit that our first thought was a worrisome idea of sandwiching metal surface transducers between a helmet and one’s skull (and being one crash away from the helmet embedding said transducers…) but happily [Matlek]’s creation is nothing of the sort.

A 3D printed rack and pinon provides adjustability and stable contact with the “sweet spot” behind each ear.

The bone conduction is cleverly achieved by driving small DC motors with an audio signal through a TPA2012 based audio amplifier, which is powered by a single 18650 cell. By using motors in place of speakers, and using a 3D printed enclosure to hold the motors up to a sweet spot just behind the ears, it’s possible to play music that only the wearer can hear and does not block environmental sounds.

[Matlek] didn’t just throw this together, either. This design was the result of researching bone conduction audio, gathering a variety of different components to use as transducers, testing which performed best, and testing different locations on the body. Just behind the ear was the sweet spot, with the bony area having good accessibility to a helmet-mounted solution. Amusingly, due to the contact between the motors and the rest of the hardware, the helmet itself acts as a large (but weak) speaker and faint music is audible from close range. [Matlek] plans to isolate the motors from the rest of the assembly to prevent this.

Another good way to get audio to transmit via bone conduction? Send it through the teeth. While maybe not the best option for a bike rider, biting down on this metal rod sends audio straight to your inner ear.