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Musical Sensor Interface Known as Media Interface Technology
Written by admin   
Wednesday, 09 March 2011 00:00

Authors: admin

A hybrid network of tangled audio technology, based around turntable decks, guitar strings, and optical sound designs is known as the CREATE USB microcontroller which is used for this musical sensor interface. Several of the most crucial audio technology inventions from the previous century being merged into a hybrid object were the goal of this Media Interface Technology. A continuum of audio technology interaction from the most physical hands-on of the vibrating string to the abstracted turntable control of pre-recorded data, to non-physical control data in optical and electronic form, and finally to the completely abstracted and malleable digital domain are embodied in this hack. The main view of the device is shown below followed by the original turntable acquired.

Musical Sensor Interface Known as Media Interface Technology

Musical Sensor Interface Known as Media Interface Technology

A Technics SLQ350 turntable is used as the main body of the device which can house the additional electronics using its expanded body. According to embedded hardware code running on a Microchip PIC based circuit embedded within the turntable, it communicates with the computer through USB using the Human Input Device and Force Feedback joystick protocols. The side-spray and rear view of the body are shown below.

Musical Sensor Interface Known as Media Interface Technology

Musical Sensor Interface Known as Media Interface Technology

A wooden frame is used to suspend a guitar string in tension across the turntable body. By contacting between the string and wooden frame, the original tonearm of the turntable serves as a freely movable bottleneck as shown below. Through the tonearm body, the vibration of the string is picked up by the stylus shown below. It will be amplified and routed to the computer for processing. A piezo contact mic mounted in the frame collects the vibrations from the 5 additional strings mounted to the wooden frame as fixed tuning sources.

Musical Sensor Interface Known as Media Interface Technology

Musical Sensor Interface Known as Media Interface Technology

The disks prepared with black, white, and gray scale patterns are mounted upon the turntable platter. Above the optical platter is a second tonearm taken from another turntable. Instead of using the stylus, it had a mouse IR receiver mounted internally and each side has a pair of IR LEDs. The optical reflectivity of the section of the platter under this tonearm in converted into an analog voltage by the IR LEDs integrated into a simple circuit. The PIC converts the analog voltage to a digital 8-bit signal that is routed via USB to the computer. The IR circuit is shown below.

The optical arm shown below contains a servo motor which determines the optical tonearm angle. The PIC controls the motor under USB control from the computer using the Force Feedback gamepad protocol. The pulse signals at a period of around 33ms are received by the servo. To specify the desired degree of rotation of the motor, its pulse width varies between 1.0 and 2.0ms.

Musical Sensor Interface Known as Media Interface Technology

Musical Sensor Interface Known as Media Interface Technology

The image below shows the turntable motor control where the internal direct-drive electromagnetic motor of the turntable operates at specific frequencies. To maintain these velocities, a pair of Hall Effect sensors is incorporated by the control circuit. An effective PWM control technique is implemented by using a MOSFET based circuit to connect and disconnect the 12V power of turntable from its motor at a high rate in order to gain speed control over the motor. Using the force feedback protocol, the PIC software allows the desired frequency for the motor to be specified. Also shown is the MOSFET circuit.

Musical Sensor Interface Known as Media Interface Technology

Musical Sensor Interface Known as Media Interface Technology

To indicate the accuracy of the frequency of rotation of the platter, the turntable platter is bordered by alternate black and silver stripes, intended for use with a strobe light.

Read more: http://www.hackolog.com/2010/12/02/musical-sensor-interface-known-as-media-interface-technology/



Last Updated on Wednesday, 09 March 2011 02:49