Sight And Sound Combine In This Engaging Synthesizer Sculpture

October 23, 2022 by Dan Maloney 2 Comments

We’ll always have a soft spot for circuit sculpture projects; anything with components supported on nice tidy rows of brass wires always captures our imagination. But add to that a little bit of light and a lot of sound, and you get something like this hybrid synthesizer sculpture that really commands attention.

[Eirik Brandal] calls his creation “corwin point,” and describes it as “a generative dual voice analog synthesizer.” It’s built with a wide-open architecture that invites exploration and serves to pull the eyes — and ears — into the piece. The lowest level of the sculpture has all the “boring” digital stuff — an ESP32, the LED drivers, and the digital-to-analog converters. The next level up has the more visually interesting analog circuits, built mainly “dead-bug” style on a framework of brass wires. The user interface, mainly a series of pots and switches, lives on this level, as does a SeeedStudio WIO terminal, which is used to display a spectrum analyzer of the sounds generated.

Moving up a bit, there’s a seemingly incongruous vacuum tube overdrive along with a power amp and speaker in an acrylic enclosure. A vertical element of thick acrylic towers over all and houses the synth’s delay line, and the light pipes that snake through the sculpture pulse in time with sequencer events. The video below shows the synth in action — the music that it generates never really sounds the same twice, and sounds like nothing we’ve heard before, except perhaps briefly when we heard something like the background music from Logan’s Run.

Hats off to [Eirik] for another great-looking and great-sounding build; you may remember that his “cwymriad” caught our attention earlier this year.

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A man playing an accordion-like instrument made from two Commodore 64s

The Commodordion Turns Two C64s Into A Single Instrument

October 22, 2022 by Robin Kearey 16 Comments

One of the main reasons the Commodore 64 became an icon of the 1980s was its MOS 6581 “SID” sound chip that gave it audio capabilities well beyond those of other microcomputers of the 8-bit era. The SID became something of a legend by itself among chiptune enthusiasts, and several electronic instruments have been designed that generate their sound through a SID chip. Not many of those look anything like traditional musical instruments however, so we’re delighted to see [Linus Åkesson]’s new project: two Commodore 64s joined back-to-back using a bellows to form a wonderful new instrument called the Commodordion. It can be played in a similar way one plays a traditional accordion: melodies are played with the right hand, chords with the left, and volume is adjusted by varying the pressure in the bellows.

The two computers are basically unmodified, and boot Commodore BASIC like they normally would. A custom circuit board emulates a cassette player and provides the software to be loaded into memory. Both computers run the same program and can be switched between the right-hand and left-hand role by pressing a specific key combination. The software in question is called Qwertuoso, and basically maps notes and various features of the SID chip to keys on the Commodore’s keyboard.

Of course, it’s the bellows that makes this instrument a true member of the accordion family. Made from 5.25″ floppy disks and sticky tape, it forms a more-or-less air-tight system linking the two computers. The airflow in the bellows is measured through a microphone placed next to the air intake: the amount of noise generated is roughly proportional to the amount of air being expelled or inhaled. This information is then used to modulate the volume generated by the two SID chips.

By [Linus]’s own admission it’s not the most ergonomic of instruments, so we’re doubly impressed by the amount of skill he demonstrates while playing it in the video embedded below. It’s not the first time either that he has turned a Commodore 64 into a musical instrument: he previously built a church organ and a theremin. While the Commodordion may look complicated, it’s actually much simpler in construction than a mechanical accordion.

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Lego Plays Electronic Drums

October 22, 2022 by Danie Conradie 15 Comments

The ability to quickly try out an idea, and then expand and develop it, is what rapid prototyping is all about. Although we tend to think of 3D printing when rapid prototyping is mentioned, [Brick Technology] reminds us of the power of Lego, as he rapidly builds and improves an electromechanical drum machine.

Using Lego Technic pieces, he starts with a simple music box-style drum with moveable pins that pluck on spring-loaded levers, which in turn hit piezoelectric discs. The electronics side is simple, with the discs wired to a Roland sound module from an existing electronic drum kit. With the ability to instantly adjust, add and remove pieces, he quickly finds and fixes the problem of getting eleven hammer mechanisms together and working smoothly.

To get around the limited pin space on the drum and increase the length and variation potential of the rhythms, [Brick Technology] moved to a belt design that can accommodate significantly more pins. He also added an electric motor and various gearbox ratios for consistent and adjustable tempo. Together with his water vortex ball machine, he makes us think our workshops probably need a few hundred Lego Technic pieces.

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An LCD mounted inside a Roland synthesizer

Reverse-Engineering A Display Protocol To Repair A Roland Synthesizer

October 15, 2022 by Robin Kearey 26 Comments

Repairing electronic devices isn’t as hard as it used to be. Thanks to the internet, it’s easy to find datasheets and application notes for any standard component inside your gadget, and once you’ve found the faulty one, you simply buy a replacement from one of a million web shops — assuming you don’t end up with a fake, of course. When it comes to non-standard components, however, things get more difficult, as [dpeddi] found out when a friend asked him for help in repairing a Roland Juno-G synthesizer with a broken display.

The main issue here was the fact that the display in question was a custom design, with no replacement or documentation available. The only thing [dpeddi] could figure out from the service manual was the basic pinout, which showed a parallel interface with two lines labelled “chip select” — an indication that the display contained two separate controllers. But the exact protocol and data format was not documented, so [dpeddi] brought out his logic analyzer to try and decode the signals generated by the synthesizer.

After a bit of trial and error, he was able to figure out the protocol: it looked like the display contained two KS0713-type LCD controllers, each controlling one half of the screen. Finding a compatible replacement was still proving difficult, so [dpeddi] decided instead to decode the original signals using a microcontroller and show the picture on a modern LCD driven by SPI. After some intial experiments with an ESP32, it turned out that the task of reading two reasonably fast parallel buses and driving an even faster serial one was a bit too much for the ESP, so [dpeddi] upgraded to a Raspberry Pi Pico. This worked a treat, and thanks to a 3D-printed mounting bracket, the new display also fit snugly inside the Roland’s case.

The Pico’s code is available on [dpeddi]’s GitHub page, so if you’ve also got a dodgy display in your Juno-G you can simply download it and use it to plug in a brand-new display. However, the method of reverse-engineering an existing display protocol and translating it to that of a new one is pretty universal and should come in handy when working with any type of electronic device: say, a vintage calculator or multimeter, or even another synthesizer.

Arduino Lo-Fi Orchestra closeup thumbnail

Lo-Fi Orchestra Learns Tubular Bells

October 14, 2022 by Dave Walker 4 Comments

Hardware projects often fall into three categories: Those that flash lights, those that make sounds and those that move. This virtuoso performance by [Kevin]’s “Lo-Fi Orchestra” manages all three, whilst doing an excellent job of reproducing the 1973 musical classic Tubular Bells by Mike Oldfield.

Producing decent polyphonic sounds of different timbres simultaneously is a challenge for simple microcontroller boards like Arduinos, so [Kevin] has embraced the “More is more” philosophy and split up the job of sound generation in much the same way as a traditional orchestra might. Altogether, 11 Arduino Nanos, 6 Arduino Unos, an Arduino Pro Mini, an Adafruit Feather 32u4, and a Raspberry Pi running MT32-Pi make up this electronic ensemble.

Arduino servo drumkit — Arduino Servo & Relay Drumkit

The servo & relay drumkit is a particular highlight, providing some physical sounds to go along with the otherwise solid-state generation.

The whole project is “conducted” over MIDI and the flashing sequencer in the middle gives a visual indication of the music that is almost hypnotic. The performance is split into two videos (after the break), and will be familiar to fans of 70’s music and classic horror movies alike. We’re astonished how accurately [Kevin] has captured the mood of the original recording.

If this all looks slightly familiar, it may be because we have covered the Lo-Fi Orchestra before, when it entertained us with a rousing rendition of Gustav Holst’s Planets Suite. If you’re more interested in real Tubular Bells than synthesized ones, then check out this MIDI-controlled set from 2013. Continue reading “Lo-Fi Orchestra Learns Tubular Bells“ →

Fixing A 30-year Old Roland Bug

October 5, 2022 by Matthew Carlson 12 Comments

The Roland CM-500 is a digital synthesizer sound module released in 1991 that combines two incredibly powerful engines into one unit. However, in 2005 enthusiasts of the Roland MT-25 (one of the engines that went into the CM-500) noticed a difference between the vibrato rate on the MT-25 and the CM-500, rendering it less useful as now midi files would need to be adjusted before they sounded correct. Now thirty-something years later, there is a fix through the efforts of [Sergey Mikayev] and a fantastic writeup by [Cloudschatze].

They reached out to Roland Japan, who decided that since the device’s lifecycle had ended, no investigation was warranted. That led the community to start comparing the differences between the two systems. One noticeable difference was the change from an Intel 8098 to an 80C198. In theory, the latter is a superset of the former, but there are a few differences. First, the crystal frequency is divided by three rather than two, which means the period of the LFO would change even if the crystal stayed the same. Changing the 12 MHz crystal out for 8 MHz gave the LFO the correct period, but it broke the timings on the MIDI connection. However, this is just setting the serial baud rate divisor, which requires changing a few bytes.

Replace the ROM chip with a socket so you can slot your newly flashed PDIP-28 64kx8 ROM into a quick desoldering. Then swap the crystal, and you’ll have a machine that matches the MT-25 perfectly. The forum post has comparison audio files for your enjoyment. Finally, if you’re curious about other fixes requiring an inspiring amount of effort and dedication, here’s a game installer that was brought back from the dead by a determined hacker.

Trombone Controls Virtual Trombone

September 27, 2022 by Bryan Cockfield 5 Comments

Guitar Hero was a cultural phenomenon a little over a decade ago, and showed that there was a real fun time to be had playing a virtual instrument on a controller. There are several other similar games available now for different instruments, including one called Trombone Champ that [Hung Truong] is a fan of which replaces the traditional guitar with a trombone. The sliding action of a trombone is significantly different than the frets of a guitar, making it a unique challenge in a video game. But an extra challenge is building a controller for the game that works by playing a real trombone.

Unlike a guitar which can easily map finger positions to buttons, mapping a more analog instrument like a trombone with its continuous slide to a digital space is a little harder. The approach here was to use an ESP32 and program it to send mouse inputs to a computer. First, an air pressure sensor was added to the bell of the trombone, so that when air is passing through it a mouse click is registered, which tells the computer that a note is currently being played. Second, a mouse position is generated by the position of the slide by using a time-of-flight sensor, also mounted to the bell. The ESP32 sends these mouse signals to the computer which are then used as inputs for the game.

While [Hung Truong] found that his sensors were not of the highest quality, he did find the latency of the control interface, and the control interface itself, to be relatively successful. With some tuning of the sensors he figures that this could be a much more effective device than the current prototype. If you’re wondering if the guitar hero equivalent exists or not, take a look at this classic hack from ’09.

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