tinyQuan

tinyQuan is a CV quantizer based on Arduino with more than a hundred scales.

Check out this short demo of an earlier and buggier version of the prototype.

Input

• CV-in (0-5V)

Output

• CV-out (0-5V)
• Trigger-out

Controls:

• Encoder 1
  • Rotate to change scale
  • Push to activate/deactivate in-scale CV mode. When the mode is on the little indicator appears solid.
• Encoder 2
  • Rotate to change root note
  • Push to switch between piano and beatstep pro layout

Comments

tinyQuan is rooted on C at 0V.

Check the I2C addresses for the MCP4725, ADS1115, and SSD1306. The default ones for mines were 0x60, 0x48 and 0x3D.

If using breakboards for the MCP4725/ADS1115/SSD1306 (this schematics assumes you are) you might want to scratch the pull up resistors on any two of the three as per the I2C standard.

In-scale CV mode

This mode when active (default) splits each volt in as many bins as there are notes in the scale. Notes will therefore be separated by the same ΔCV in a given scale, but different ΔCV across different scales.

When deactivated tinyQuan follows the 1V/Oct convention. Semitones are always separated by a ΔCV of 83mV. Not all of them appear in a given scale and thus notes are not equally separated by the same ΔCV.

Trigger width

The trigger width is set to 1ms. Change trigger_length for something longer, or change all instances of millis to micros to shorten it even more.

Arduino library requirements

• Adafruit GFX
• Adafruit SSD1306
• Rob Tillaart's MCP4725 and ADS1X15

TODO

• This is a very rough prototype. There are no overvoltage protection on any jack. The code is probably still full of bug and certainly not as efficient as it could. The CV-out DAC is 12-bit and should probably be more precise. The CV-in ADC is 16-bit and has 4 ports which is way overkill. Changing either would require complete retuning.

• Add S&H input jack and code.

• Change in-out CV ranges to ±5V. It's annoying having to use unipolar LFOs and S&H as input. Worst of all you can't go under the root note!

• Overvoltage and input protection.

BOM

• 1x Arduino Nano
• 1x SSD1608 128x64 (OLED display)
• 1x ADS1115 (CV-in ADC)
• 1x MCP4725 (CV-out DAC)
• 2x Full-cycle rotary encoder with push-switch
• 3x 1K resistors
• 11x 10K resistors
• 1x 100pF capacitor
• 4x 10nF capacitors
• 2x 100nF capacitors
• 2x 3.5mm TS jacks
• 1x 3.5mm TS jack with switch
• LM317 MOSFET
• 1x trimpot (I use a multi-turn to precisely trim to 5.000V)
• 5V-12V power supply of your choice although LM317 will tolerate up to 37V

Schematics