Control Voltage (CV)/Gate to MIDI 

 

The CV/Gate to MIDI unit is capable of converting the output control/gate voltages from a monophonic synthesiser  to a MIDI  note-on/note-off data commands. The unit works with linear CV out Volts/Oct where 0 volt is set to C1 and 4 volt is set to C5. However different MIDI note octave ranges can be pre-programmed, if required.  Each semi-tone is equal to (1/12 = 0.08333 Volt). The gate output voltage from the synthesiser can be between 5 to 15 volts when a note is ON and 0 volt when the note is OFF.

 

 

*Click to Enlarge*

CONTROL Voltage to MIDI ITEM#: CV2MIDI PRICE:  €45.00

 

The Control Voltage (CV)/Gate to MIDI unit utilizes:

• An assembled, built and tested Arduino board including a suitable pre-programmed Atmega168,
• 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 transmit MIDI channel (1-16) can be selected by a 4-way DIP switch. 
• The velocity byte is preset to half of the maximum value.
•  The CV to MIDI unit is monophonic

 

 

 

The Control Voltage (CV)/Gate to MIDI unit  also requires:

• A 9v battery or equivalent DC power source,
• A Gate trigger LED, and transistor driver,
• A variable 10k linear potentiometer for scale tuning,
• A variable 10k linear potentiometer for volume adjustment (optional), plus a 5.1 Volt Zener diode and associated 1k series resistor (optional)

 

 

MIDI IN/OUT Wiring:

 

*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.

 

 

 

Circuit Schematic:

A circuit schematic of the Control Voltage (CV)/Gate to MIDI unit shows the Input/Output connections. 

 

Power Supply:

The  Arduino/Freeduino etc. Diecimila can be powered via the USB connection or with an external power supply. The power source is selected by the PWR_SEL jumper. To power the board from the USB connection, place it on the two pins closest to the USB connector, for an external power supply, the two pins closest to the external power jack.

 

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.

 

Note that with the Arduino Duemilanove or Mega the power input selection (USB/EXT.) is automatically selected.

   

Download:

Open the  source code file and copy and paste it into the Arduino programme and save it as a .PDE file.

   

 

 

 

 

 

Tuning to a MIDI octave range scale:

When the Control Voltage (CV) is applied to the CV of the MIDI unit, the potentiometer can be adjusted to give a MIDI C7(96) note out when the CV is 4 volts. This tunes the MIDI unit to the scale shown in Table 1 and the rest of the ranges are  tuned. 

 

 

So the CV potentiometer needs to be adjusted to obtain 1.89 Volts out when 4 Volts CV is applied.

 

The MIDI Note Number to Pitch/Frequency is available and

the MIDI Note Numbers for Different Octaves table is available also.

 

The unit can be used with the Moog Music Etherwave Theremin.