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Twelvey provides a compact control voltage interface for one “octave” of musical notes. Twelve voltage divider circuits send distinct voltages through a common output port.
This device contains twelve parallel voltage divider circuits, each providing between +5V and +6V of “control voltage” for a CV-based sound synthesizer. By adding “keys” (e.g., momentary button switches), this circuit will approximate the 1V/Oct implementation common on several analog synthesizer platforms, as follows:
Input Voltage (V)
Output Voltage (V)
Audio output may or may not equate to a true musical “octave;” this device can be connected to any number of possible synthesizers under any number of possible conditions. The output should, however, constitute twelve distinct voltages, increasing regularly from lowest to highest, which may approximate an octave-like scale.
LCSC Part Number
40V 3A 550mV @ 3A Schottky Barrier Diodes
D1, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, D12
R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, R12, R13, R15, R16, R17, R18, R19, R20, R21, R22, R23, R24, R25
To use this device as a CV controller, connect the following:
- A power supply
- Buttons or switches
- An output jack
This design features a space (currently unused) for a built-in dual oscillator based on Texas Instruments’ Dual 2-Input NAND Gate With Schmitt-Trigger Inputs (SN74LVC2G132). Certain locations on the PCB (Ports 1-7, 3G, 7G, and IC SW) are designed to work with this planned feature.