The Carte Blanche Delta-Sigma Audio and SVGA Video IO Board
The AVIO internal board provides both Audio and Video capability to Carte Blanche.
Audio and Video Inputs and Outputs have defined cable paths out of the system.
The CBAVI board fits neatly inline with Carte Blanche and provides maximum seperation to avoid annoying Delta Sigma interference.
The Audio Video IO board brings Delta-Sigma stereo audio capability to the Carte Blanche board. By connecting the CBAV IO board in-line to the existing SVGA interface and utilising the unused SDA and SCL pins of the video circuit as Delta-Sigma Audio, full stereo audio capability can be realised.
Audio is presented on a standard 3.5mm Audio jack suitable for connection to typical desktop computer speakers or volume controlled headphones. The board is mounted inside the Apple IIe case where it can drive a set of speakers direct with a small modification. The audio system is based on a Delta-Sigma Digital to Analogue converter technique in conjunction with a resistor-capacitor roll off network and includes digital control of both output frequency and volume level of each channel.
For Audio based designs requiring resources needed to implement or emulate a two tone board, a Samspeech card or Mocking board, the CBAV IO board is ideal and low cost.
Information regarding PCB layout, Schematics and Delta Sigma implementation principals can be found here;