Audio Infuser 4700

"Not your grandpa's stereo"

Wi-Fi Enabled

Although completely hidden from sight, the Raspberry Pi is really the star of the whole project.  It’s what kicked this project off in the first place, and is what really sets this machine apart from any average record player or stereo device.  It’s running Raspbian Wheezy, the basic Linux OS built for the Pi, which is in turn running a program called Shairport.  

Shairport is a reverse engineered version of Apple AirPlay made available to the open source Pi community.  It effectively turns a Pi into an AirPlay, allowing seamless integration and compatibility with any (audio) system that would normally interact with a real AirPlay.  iPhones and other Mac OS products can send music to it without any additional software, and Windows/Adroid based devices can also transmit to it with the help of a third party application.  Any major audio playing app should be supported, including Spotify, iTunes, and Pandora.  


The Arcade

Accompanying the Pi itself is a USB hub, USB sound card,  Wi-Fi adapter, and extensions to the rear I/O panel for ethernet, HDMI, and USB.  The rear USB port is designed for use with a USB game pad.  Also installed on the Pi is an arcade emulator, AdvMAME.  By switching the CRT to video input mode, and hitting one of the Function Select buttons, a game of either PacMan or Asteroids is playable on the screen, complete with sound and a fully functional mini control panel.


The Arduino

Drawing power from the USB hub is an Arduino which drives two servo motors.  These servo motors control CRT dials that would not be otherwise accessible.  Mounted on the faceplate is a potentiometer and a single-pole-single-throw toggle switch.  When you turn the potentiometer labeled Brightness, the Arduino accepts this input and rotates a corresponding servo to adjust the CRT’s brightness knob.   When you toggle the Video Source switch, a second servo moves an input switch on the CRT to adjust video input source.  

This functionality is required to allow flexibility in how the CRT image is displayed.  A higher brightness value and the CRT will display a glowing white oscilloscope wave.  A lower brightness and the wave will be a colored gradient.   The gradient is customizable by adjusting a series of internal potentiometers directly on the tube, which defines how rays are fired on a hardware level.  

The Video Source switch toggles the input from the Pi’s video input to “None” which is just static noise.  Static is desirable when in Oscillation mode in order to have a unified source image.  Remember the vertical coils of the CRT are still connected to the video source, so even in Oscillation mode you will see a trace (spanning vertically, but condensed to just a single pixel wide) of whatever video is being fed to the CRT (either the Pi or static noise).  This could offer future possibilities of running a software based music visualized on the Pi that perhaps pulses color based on beat, which would then show up in unison while the wave oscillates.  


>> Continue on to read about The Amplifier

by Todd Kumpf   // //   //   @toddkay