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. The wiring connections are shown in the CV to MIDI Layout diagram.

• 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 utilizes:

• A Printed Circuit Board (PCB), 
• A pre-programmed 16F877 PIC,
• The 4-way DIP switch which selects the MIDI transmit channel via DIP switches 1-4 (See Table 2) 
• The  power-on LED,
• A Gate trigger LED,
• A variable potentiometer for scale tuning,
• A 9 volt battery connector,
• A MIDI 5-pin DIN output socket, see Circuit Diagram
• A screw terminal connector for an external 9-12 volts DC supply
• Two  screw terminal connectors for connecting the external CV and gate signals

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

• a 9v battery or equivalent DC power source

Tuning to a MIDI octave range scale:

When the Control Voltage (CV) is applied to the CV to MIDI unit the potentiometer can be adjusted to give a MIDI C5 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.

The pitch/frequency for each MIDI note is shown in the MIDI to Frequency table. Also the MIDI Note Numbers for Different Octaves table is available.