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



This unit allows the use  of a synthesiser/keyboard as a "master program selector" without the notes played on the main keyboard transmitting to a secondary synthesiser/module. The unit only allows MIDI Program Change commands to pass through, all other MIDI commands are blocked.


The MIDI Program Change Filter can be used to reduce MIDI throughput by removing MIDI System mesages. Also it allows one channel to operate a particular sound module/synthesiser.



MIDI Program Change Filter


PRICE:  €50.00







The MIDI Program Change Filter unit utilizes:

  • An Arduino board including a suitable pre-programmed microcontroller,
  • A 2.1mm power socket, and associated LED, 
  • A MIDI detection LED,
  • A MIDI 5-pin DIN input socket,
  • A MIDI 5-pin DIN output socket, 
  • The circuit schematic is available,
  • The MIDI IN/OUT circuit schematic is also available.



The MIDI Program Change Filter  requires:

  • A 9 Volt battery or equivalent 9 Volt DC power source



The unit detects the incoming MIDI data and if the data is MIDI Program Change then the MIDI data is transferred to the MIDI output.


However if other MIDI data is detected, it is filtered out and it is not transferred to the output, including any non-channel events are filtered out. So any System Common, Realtime or Exclusive events are ignored.






     *Click to Enlarge*

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.






MIDI Specification: 

The MIDI Program Change Filter does not change the incoming MIDI channel (1-16). The system will also work with MIDI running status. Also the 4-way DIL switchon the MIDI IN/OUT board is not used in this project.


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.