The Carte Blanche Delta-Sigma Audio and SVGA Video IO Board
The AVIO board plus in-line with the existing SVGA cable to provide both Audio and Video capability to Carte Blanche.
Audio and Video Inputs and Outputs are clearly marked.
An additional 10 pin copy of the CB IO port is provided for additional external displays or to use the IO in other functions.
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 may also be optionally mounted inside the Apple IIe case where it can drive a set of speakers direct. The audio system is based on a Delta-Sigma Digital to Analog 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;