MCO

MIDI Controllable Oscillator with Detune Support.

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$20
MCO

This is a MIDI Controllable Oscillator (MCO) that generates two square waves. One is the main oscillator, and the other is a detuned oscillator that can be tuned up to 12 semitones down.

Square waves are generated digitally and then mixed together using analog circuitry.

Functionality

Here are some ideas:

  • Use SVF and ENV with a short pulse envelope to create ACID sounds.
  • Use LOW with a gate input to produce solid bass sounds.
  • Use SVF and ENV with a sustained envelope for lead sounds.
  • Use Drive for more aggressive sounds.

Inputs

Inputs

  1. MIDI MIDI input to control the oscillator
  2. NC Not connected
  3. NC Not connected
  4. TX Debug pin for the microcontroller
  5. UPDI Programming pin for the microcontroller

Outputs

  1. MIDI MIDI THRU (passthrough) output
  2. OUT Oscillator Output
  3. OUT Oscillator Output
  4. GATE Gate trigger from the MIDI input
  5. VEL Velocity CV from the MIDI input

Controls

  • DETUNE: Controls the detune amount. Left is detuned up to 12 semitones down, and right is almost in sync.
  • MIX: Mixes the detune oscillator with the main oscillator. Left is no mix, and right is full mix.

MIDI

  • Use any MIDI note to trigger the oscillator (this is a monophonic oscillator).
  • Accept velocity and output it as a CV signal. (Velocity does not affect the oscillator.)

Additional Parts

This section is only relevant if you are buying the semi-assembled module. You have to source & solder the following parts. You can check our guide on common parts for where to source these components.

  • 2.54mm Header Pins (5-pin) - 2
  • Circular Pin Header Sockets (5-pin) - 2
  • 50K Potentiometers - 2