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Accordions are available many shapes. Some have a bit of piano keyboard whereas others have a grid of black and white buttons set roughly within the form of a parallelogram. I’ve been fascinated by this “chromatic-button” structure for a very long time. I spotted that the buttons are staggered identical to the keys on a typewriter, and this perception someway was a blurry imaginative and prescient of an accordion constructed from a pair of Nineteen Eighties dwelling computer systems—these machines usually sported a built-in keyboard in a case large enough to type the 2 ends of an accordion. The thought was intriguing—however wouldn’t it actually work?
I’m an skilled
Commodore 64 programmer, so it was an apparent selection for me to make use of that machine for the accordion ends. As a retrocomputing fanatic, I wished to make use of classic C64s with minimal modifications reasonably than, say, gutting the pc circumstances and placing fashionable tools inside.
As for what would go between the ends, accordion bellows are a set of semi-rigid sheets, usually rectangular with a gap within the center. The sheets are hooked up to one another alternating between the inside and outer edges. Another flash of perception: The bellows may very well be constituted of a stack of 5.25-inch floppy disks.
Now I had a number of compelling concepts that appeared to work collectively. I secured a big amount of dangerous floppies from a fellow C64 fanatic. And then, armed with every thing I wanted and keen to start out, I used to be promptly distracted by different tasks.
Some of those tasks concerned methods of taking part in music stay on C64 computer systems. The thought to mannequin a musical keyboard structure after the chromatic-button accordion grew to become a standalone C64 program launched to the general public known as
Qwertuoso.
In addition to 2 classic Commodore 64s [left], the Commodordion has a microphone for detecting air stream by the bellows, and buttons for turning on the ability and controlling a tape-deck emulator [top right]. The bellows are constituted of tape and 5.25-inch floppy disks [middle right]. One supporting board incorporates a microcontroller to measure the airflow and blend the audio indicators, a second shops the accordion software program and emulates a cassette participant, and a 3rd acts as an influence hub.James Provost
That might nicely have been the tip of it, however I had all these disks on my fingers, so I made a decision to go forward and attempt to craft a bellows in any case. The physique of a floppy disk is constituted of a folded sheet of plastic, which I unfolded to type the bellow’s segments. But I had underestimated the issue of air leakage. While the floppy-disk materials is hermetic, the seams aren’t. In the tip I needed to patch the entire thing up with a number of layers of tape to get the air to remain inside.
An actual accordion makes use of the bellows to push air over reeds to make them vibrate. How quick the bellows is pumped determines the accordion’s loudness. So I wanted a method to sense how briskly air was being squeezed out of my floppy-disk bellows as I performed.
This was trickier than I had anticipated. I went by a number of failed designs together with one impressed by the
“hot wire” sensors utilized in gas injection methods. Then sooner or later, I used to be watching a video and I spotted that an individual within the video was shouting with the intention to overcome noise attributable to wind hitting his microphone. That was the breakthrough I wanted! The answer turned out to be a small microphone, mounted at an angle simply outdoors a small gap within the bellows.
Air flowing into or out of the opening passes over the microphone, and the ensuing turbulence turns into audio noise. The depth of the noise is measured, in my case by an
ATmega8 microcontroller, and is used to find out the output quantity of the instrument.
The bellows is hooked up to a easy body constructed from wooden and acrylic, which additionally holds the C64s in addition to three boards with supporting electronics. One of those is an influence hub that takes in 5 and 12 volts of DC electrical energy from two household-power adapters and distributes it to the varied elements. For ergonomic causes, reasonably than utilizing the conventional socket on the C64s right-hand sides, I fed energy into the C64s by wires handed by the case and immediately soldered to the motherboards.
The Commodordion is performed through the use of the keys on the Commodore 64s and squeezing the bellows between. Air transferring by the bellows creates a loud or delicate noise relying on how arduous the bellows are squeezed. A microcontroller working an envelope-following program controls a multiplexing digital-to-audio converter that units the ultimate quantity of the mixed sound from the C64s.
James Provost
A second board emulates Commodore’s datasette tape recorder. This shops the Qwertuoso program. Once the C64s are turned on, a keyboard shortcut constructed into the unique OS directs the pc to load from tape. The closing board accommodates the microcontroller monitoring the bellows’ microphone and mixers that mix the analog sound generated by every C64s
6581 SID audio chip and adjusts the quantity as per the bellows air sensor. The audio sign is then handed to an exterior amplified loudspeaker to supply sound.
In order to achieve the keys on the left-hand aspect when the bellows is prolonged, my hand must bend fairly far across the fringe of what I dubbed
the Commodordion. This places a number of pressure on the hand, wrist, and arm. Partly because of this, I developed a sequencer for the left-hand-side machine, whereby I can program a easy beat or sample and have it repeat mechanically. With this, I solely must press keys on the left-hand aspect often, to modify chords.
The Commodordion
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As a musician, I’ve to take ergonomics critically. When you be taught to play a bit of music, you follow the identical motions again and again for hours. If these motions trigger pressure you may simply damage your physique. So, sadly, I’ve to limit myself to taking part in the Commodordion solely often, and solely play quite simple components with the left hand.
On the opposite hand, the right-hand aspect feels completely effective, and that’s very encouraging: I’ll use that as a place to begin as I proceed to discover the design house of devices constituted of previous computer systems. In that gentle, the Commodordion wasn’t the ultimate purpose in any case, however an necessary piece of scaffolding for my subsequent inventive endeavor.
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