Build your own MIDI circuits
Frequently Asked Questions.
MIDI & Music
MIDI and Music Information

MIDI Trombone


This is a MIDI wind controller. The Trombone interface design uses a pressure sensor, suitable amplifier and 14 switches to produce an  output which is translated into velocity sensitive MIDI Note ON data.


The 14 switches are defined as 5 Position switches, 4 Partial switches and Octave 2,3,4,5 and 6 switches. The mapping of the 14 switches  is available. The breath pressure sensor should have the full voltage range (0-5V) to use for velocity/volume. Other switch mapping settings are available on request. The MIDI Channel is preset to MIDI channel 1. The unit also has Pitch Bend and Modulation control inputs. 







PRICE:  €45.00


   *Click to Enlarge*
pressure_sensor.jpg (23113 bytes) MIDI Trombone & Pressure


ITEM#: MIDITrombonePressure

PRICE:  €59.00







The MIDI Trombone interface utilizes:

  • An Arduino including a suitable pre-programmed Atmega168,
  • A 2.1mm power socket, and associated LED, 
  • The MIDI channel is preset to channel 1,
  • 2 Analog inputs for Modulation and Pitch Bend,
  • A MIDI 5-pin DIN output socket,
  • A MIDI activity associated LED,
  • 14 off 0.1" pin-terminal switch inputs,





The MIDI Trombone interface requires:

  • A 9 Volt battery or equivalent 9 Volt DC power source,
  • 14 momentary action (SPST) switches,
  • 2 off 10k ohm linear potententiometers for MIDI Modulation and Pitch Bend,
  • A Breath pressure sensor. 



Circuit Schematic:

A circuit schematic of the MIDI Trombone interface shows the Input Switch connections. The HEX switch mapping  for the input switches is also available.


You can obtain a Freescale Semiconductor Breath Pressure sensor type MPXV5010G  (or similar type) from Digikey and other sources. 

Details of the MPXV5010G  pin connections are available. From the breath sensor, Pin 2 is connected to +5 Volt, Pin 3 is connected to Ground (GND) and Pin 4 is connected to the Analog pin A0, on the Arduino.


A plastic tube can be connected to the pressure sensor. It is probably a good idea to put a small pin-hole in the plastic tube near the pressure sensor to drain away moisture from your breath when you are blowing. The hole should be large enough to drain the moisture but not too large to affect the pressure sensor function.




Complete details of the MPXV5010G Freescale Semiconductor Breath Pressure sensor are also available. This is similar to the breath pressure sensor used in the Akai Electronic Wind Instrument (EWI).


Note that if the  Pitch Bend or Modulation inputs are not used they should be connected to Ground (GND), to prevent random MIDI Pitch Bend or Modulation outputs being produced. 





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






Power Supply: 

The  Arduino can be powered via the USB connection or with an external power supply. 


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.