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MIDI Program Change Filter


Program Change Filter


The MIDI Program Change Filter can be used by guitar players,
with a T-Rex Spin Doctor (preamp foot pedal for guitar) midi programmable.

When you send the first (X-number) Program Change from midi footpedal T-Rex changes the right program.

If you press again the same footswitch on midipedal (sending same program change by mistake, for example) T-rex changes into BYPASS mode (no effect). But you would prefer that the machine would not change.

So to prevent this mistake happening, this Program Change Filter is designed to block only a Program Change equal to a previous similar Program Change.




*Click to Enlarge*


Program Change Filter


PRICE:  €50.00







The MIDI Program Change Filter unit utilizes:

  • An assembled, built and tested Arduino board including a suitable pre-programmed Atmega microcontroller,
  • A 2.1mm power socket, and associated LED, 
  • A MIDI detection LED,
  • A 150mm wired MIDI 5-pin DIN input socket,
  • A 150mm wired MIDI 5-pin DIN output socket, 
  • The circuit schematic is available,.



The MIDI Program Change Filter requires:

  • A 9 Volt battery or equivalent 9 Volt DC external power source, or USB Connector.




     *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.








Power Supply:

The  Arduino can be powered via the USB connection or with an external power supply. Note that with the Arduino or Mega the power input selection (USB/EXT.) is automatically selected.


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.