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My Midi Project... ( English System )

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Hi, I am in the middle of my own midi project using several new ideas:

I have a ME Aeola piccolo without reed-pans, which I am converting to MIDI - very little space!!

I do it in such a way that the original instrument is not harmed, but can be converted back to acoustic any time!

I stick little magnets in the middle of the pads ( they may or may not have to be removed or the pads changed, if converted back ).

I introduce a thin plywood-plate between the ends and the bellows. On these plates I stick hall-effect sensors to pick up key motion. This plate will also hold all other components.


The pic shows the plate with a photo-copy of the end stuck on for easy placement of the sensors! The extra little corner will hold the socket for external connection.

Rather than interfacing the sensors to individual inputs, I use 16 bit I2C ( two wire bus ) ICs. So my 48 keys require 4 of them.

The connection between the two sides requires only 4 wires ( 2 x supply plus 2 x I2C bus ). I use a coiled telephone-cable.

I use a I2C-bus pressure-sensor!!

All inputs can be accessed by the central processor ( a very small Arduino ) with only two pins - using the I2C library!

I can bring the output-cables through a slot of the sensor-boards without any harm to the original instrument!

I have three output options:

1. I2C-bus only ( 4 lines ) for external processing ( to an external control-box )

2. MIDI output plus power in ( 3 lines )

3. MIDi out already converted to USB for direct interface to an Android / Apple-device ( which also supplies the power! ).

I use an "unusual" combination of keys to put the controller into "programming-mode", where I can alter MIDI-parameters, pitch, volume etc. with my 48 keys! So there is no need for additional buttons and controls.

I got an experimental setup to work well - but there is a lot of work still waiting for long winter-nights!!

Unfortunately - or fortunately - I don't have to earn my living by making MIDI-concertinas, so the project doesn't have a very high priority - and I doubt that I will ever make them to order - but if there is enough interest, I might give a workshop at the next German-Concertina-Meeting end of March 2015 <_<

PS: The same approach could easily be used to convert a McCann to Hayden! Or even give both options in one instrument...

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Thanks for this.


Some very nice ideas in this design approach. I hope you don't mind if I steal some of them!


Did you consider making a hexagonal PCB instead of using a piece of plywood? You are going to have mount and wire the components anyway and this would be a lot more robust.



Edited by Don Taylor
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Don, a PCB would be a great idea for mass-production. i.e. for the Hayden-project. But for a one-off I will stick to a wire-job;-)


On the other hand - you couldn't solder components through without leaking air - it would have to be surface-mounted.


Originally I had planned to drill tiny holes into the board for each pad to let a little air through if a key is pressed, but since the air-button on the piccolo is leaking, this gives me enough bellow-movement to feel realistic...

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On the other hand - you couldn't solder components through without leaking air - it would have to be surface-mounted.

Properly soldered through-hole joints are air tight. Non-soldered mechanical mounting holes might leak, though you could always put a spot of sealant on each one.

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  • 2 years later...

Hello Conzertino,


I realize this is an old post, but did you ever finish your MIDI concertina?


I had thought about the same approach: retrofitting an old non-functional concertina. I like your idea of the pads with the magnets to activate the sensors for the switches. Now I'm just building it myself but I won't be using a real concertina action, just buttons.


How much extension do you get with the coiled cable? I was considering that for left/right communication but thought I wouldn't get enough stretch without the slack falling into the bellows folds. I would like to hear how well it works as I was considering going wireless altogether and just having both halves transmit to a main module or one to the other.


The 16 bit i2c you mention I think you must mean a shift register, how well did that work for your project? I found an online site where they showed using a diode matrix, and I had thought about shift registers but decided I wanted to keep the chip count low. I'm using an Arduino Nano on each side, because I just happen to have 2 of them, fortunately there's enough inputs the matrix method can work. I'm thinking that with the shift register method perhaps you don't need the diodes?


But the main reason I'm writing is I think your idea of using the existing concertina buttons to make the patch/program changes is a great idea. I had been thinking about where I would put control buttons, but that is an elegant solution.

I bet you could trigger specific midi sequences from the controller, maybe it could recognize the first few notes of a tune set you have and then begin to play some accompaniment.

Edited by Reed Rat
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  • 4 weeks later...

Hi Reed Rat,

Just a quick note to answer one of the questions you asked Conzertino, about the coil cord. I used that approach for my scratch-built midi concertina, which used an industrial bellows, not a traditional one, but the geometry was similar. I was fully expecting the cord to get jammed in the bellows folds, but it didn't happen. I think the fact that typical telephone coil cords are a bit slippery helps. For my setup, I measured the cord so that it would loop once around the inside of the fully compressed bellows. That was enough to give an extension of well over a foot, longer than the physical limit of the bellows. FWIW, I used a 6-wire coil cord, running two power wires, two ground wires, and CAN + and - on the remaining two wires. I'm not a huge fan of I2C, and my microprocessors supported native CAN, so that was a no-think.

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