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MIDI Concertina English


MIDI Concertina

concertina_english_48.jpg (37695 bytes)


This is a design for a reedless MIDI Concertina. Some of the advantages of such an instrument are instant key changes, via MIDI, and the ability to practice with headphones (silently to the outside world).


The MIDI Concertina encoder is capable of encoding the required 48 momentary action, push to make, single pole single throw (SPST) switches to produce the equivalent MIDI note-on/note-off data commands. 


The design consists of the Arduino and the encoded switches wired via IN4148 diodes, see switches circuit diagram and a 5-Pin DIN MIDI socket. Also Hall Effect switches can be used if required.


 The design is based on a two sided diatonic keyboard with 24+24 keys for the Left hand and for the Right hand. This design is for an English Concertina  but other keys could be encoded if required.






PRICE:  €45.00


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The Concertina Encoder to MIDI Unit utilizes:

  • The MIDI channel is set to channel 1 for left and right hand 24 + 24 switches,
  • The velocity byte is preset to the maximum value,
  • An Arduino board including a suitable pre-programmed microcontroller,
  • A 2.1mm power socket, and associated LED, 
  • A MIDI 5-pin DIN output socket,
  • The switches circuit schematic is available,
  • The Program Switch and Volume control circuit is available.



The Concertina Encoder to MIDI Unit requires:

  • A 9v battery or equivalent DC power source,
  • Required 48 external switches and associated diodes, 
  • 4 Program Change switches and associated diodes,
  • 1 Volume control potentiometer between 10k ohm to 100k ohm.




Circuit Schematic:

A switches circuit schematic of the MIDI Concertina shows the switch connections.  Note that for this project the 4-way DIL switch is not required. Also the circuit for the Program Change Switches and Volume control input is available.


NOTE: If the Volume Control input Analog Pin is left unconnected then the unit will produce random MIDI volume outputs due to noise pickup on the Analog input.



Hall Effect Wiring:

 If you use Unipolar Hall Effect devices and if you use Open Collector devices you will need a Pull-Up resistor for each device.






MIDI Wiring:

The MIDI IN and OUT connections use 5-Pin 180 degree DIN sockets. Note that the MIDI wiring is polarised and the correct pins should be used. 


MIDI Concertina Wiring:

The switches are organized in a 8 x 6 matrix (48 switches) arrangement. The switch keys are wired as shown in the  Wiring diagram.


So, for example, terminal connected to D10  is wired to one side of the 8 key switches SW 0 to SW7 and the wire can be looped from one key switch to the next. Also the other sides of these switches/diodes are connected down to Arduino contacts D2 to D9.


Each of the other side of these switches SW0 to SW7 is wired to a diode on the Cathode (K) side (end of diode with stripe).

The other side of each of these diodes is looped to 7 other diodes. For example Anode (A) of diode DO is looped to D8 then to D16 then to D24 etc. down to D40 and finally to digital terminal Pin D2 on the Arduino.


The rest of the wiring is done in a similar manner.


Power Supply: 

External  power can come either from an AC-to-DC adapter  or battery. The adapter can be connected by plugging a 2.1mm center-positive plug  into the board's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector. .


The board can operate on an external supply of 7 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.