Sinu is an attempt at producing a rendition of the traditional music box. This particular rotary sequencer uses a set of eight photocells suspended above a set of eight LEDs. A 11” acrylic disk is divided into 16 slices, each containing 8 holes for the LED to shine through as it passes the “playhead.” The circular disk is place onto a direct-driven turntable motor mounted on the main enclosure. A set of nine LED push buttons, 3 rotary potentiometers, 1 linear potentiometer, 1 LED power indicator, and two switches are also mounted on the enclosure.
The functionality of the buttons A-H are to act as steps of a conventional sequencer. Button I functions as a shift button that enables the user to switch between sequences. When first powered, a sequence can be entered by pushing buttons A-H. Once this has been done, LED Q will turn on and the position marker of the sequence will flash at position 1 (LED in button A.) A second sequence can be entered by holding down button I and selecting any button B-H. When a sequence is entered on any pattern I+A-H, the corresponding LED Q-X will turn on. Each pattern I+A-H corresponds to a note in the scale specified in the program. Basically, as LED Q-X passes through the playhead containing photocell Q-X, the position marker of the sequencer iterates through the sequence. Switch O turns on the motor, and switch M reverses its direction. Linear pot P controls speed of the motor. Rotary pots J-L can be midi mapped to control any parameter desired.
Sinu is controlled using an Arduino Mega with a Arduino Motor Shield Rev3. The design consists of four custom made PCBs: photocell board, LED board, control board, and a custom Arduino shield to direct connections to pins. The custom PCB for the photocells use a 1K ohm resistor for each photocell. Voltage readings are then directed to a 5×2 header pin to send out to Main shield via ribbon cable.
The LEDs that are located beneath the photocells are controlled through the digital output pins of the Arduino, which then travel through a 220 ohm resistor, and out to the 5×2 header pin connector.
Control Board Schematic
The Control Board PCB houses all the buttons, its LEDs, and switches and pots found on the enclosure. All of the connections are then routed, via ribbon cables, to the custom Main Arduino shield which then directs each component to its corresponding pin. All programming is done in Arduino and ChucK. Arduino determines how the sequencer functions, receives pulses from each photocell, reads the sequences from a 2d array. A note-on and note-off is then sent to ChucK via serial. ChucK receives and sends MIDI out through an IAC Bus which Ableton Live receives.
The final result is an improvement of the predetermined melodic content found on the traditional music box and Modular Music Box by Sykes and Rothwell, to an extensible and expressional musical interface that one could perform a variety of techniques on.