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MIDI Piano Accordion Bass & Chords Only

 

MIDI Piano Accordion Bass & Chords Only

piano_accordion_37note.jpg (8479 bytes)

  

This is a design for a reedless MIDI Piano Accordion encoder with Bass and Chords only. Some of the advantages of such a design are to provide MIDI instrument Bass and Chord accompaniment.

  

The Accordion Chords are preset to start at MIDI Note number E4(64), on MIDI Channel 2. The Accordion Bass is preset to start at MIDI Note number A1(33), on MIDI Channel 3. The velocity byte is set to a value of 100.

 

Please note that other start note values, MIDI Channels and velocity value can be preset on request. 

  

The Bass selection is assigned to a 12x1 matrix and the Chord selection is also assigned to a 12x1 matrix. A circuit schematic of the MIDI Piano Accordion Bass and Chords Mapping

 


  

 

 

MIDI PIANO ACCORDION BASS & CHORDS ONLY

ITEM#: MIDIPIACCBASSCH

PRICE:  €45.00


 

*Click to Enlarge*

 


 

 

The MIDI Piano Accordion Bass & Chords Encoder Unit consists of:

  • An assembled  Arduino UNO, with pre-programmed micrcontroller,
  • The MIDI channels 1, 2 and 3 are preset, 
  • The MIDI channels 2 and 3 are preset, 
  • The Accordion Chords are preset to start at MIDI Note number E4(64), on MIDI Channel 2,
  • The Accordion Bass is preset to start at MIDI Note number A1(33), on MIDI Channel 3,
  • The velocity byte is set to a value of 100, but other values can be preset on request,
  • A 2.1mm power socket, and associated LED, 
  • A MIDI activity LED, 
  • USB power or external power choice,
  • A MIDI 5-pin DIN output socket.

 

 

The MIDI Piano Accordion Bass & Chords Encoder unit requires:

  • a 9v battery or equivalent DC power source
  • Suitable key-switches or magnetic reed switches or hall effect switches and associated IN4148 diodes.

 

Circuit Schematic:

This unit uses the ATmega Uno microcontroller and can be powered from an external 9 Volt DC power supply/battery or via the USB connection. 

 

 

   

Hall Effect Wiring:

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

 

 

Videos: 

Here is a video showing how the Root and Major 3rd rods/levers lift one at a time when a button is pressed and here is a video showing when a single bass chord button is pressed 3 rods/levers are mechanically activated simultaneously.

 


 

MIDI Wiring:

The MIDI  OUT connection uses a 5-Pin 180 degree DIN sockets. Note that the MIDI OUT wiring is polarised and the correct pins should be used. 

 


 

Power Supply:

The  Arduino Uno can be powered via the USB connection or with an external power supply. The power source is selected automatically. 

 

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) 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. A low dropout regulator provides improved energy efficiency.

  

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.

  


 

MIDI Keyboard Wiring:

 

STRADELLA SWITCHES FOR BASS and CHORDS:

Accordions which have had midi units fitted usually have the 12 root note/major 3rd notes served by 12 mechanical switches and the 12 notes which form the  48 chords of the Stradella System are served by another 12 switches only.


The mechanics of the bass system automatically selects the 3 notes/switches of the chord from the 12 available. i.e. the chord is formed mechanically and not digitally.


All 120 bass systems have only 12 bass/3rd  notes and 12 chord notes.

The midi Stradella Bass section is programmed to give, on Midi-Channel 3, 12 fundamental bass (root and major 3rd) notes and on Midi-Channel 2, 12 chord notes. 

 

 

PIANO ACCORDION BASS and CHORD SWITCHES:

 

For the Bass and Chord switching:

 
Switch SW0 is connected via a diode between pins D4 and D2, giving the first MIDI Number,
Switch SW1 is connected via a diode between pins D5 and D2, giving the second MIDI Number,
Switch SW2 is connected via a diode between pins D6 and D2, giving the third MIDI Number,
 
etc.