Total posts : 45366
Okay, she’s not pretty but she’s working under test conditions. I made a few minor component changes, but otherwise, the circuit shown above is it. I have the primary Audio supplied by the Sony Voice Recorder/mp3 player and the output goes to a set of computer speakers. The audio sounds great running through the analog switch. (I can’t notice a difference). I may still want to increase the gain some to allow for very quiet passage nuicance triggering. I also may want to add a Schmit trigger to the comparitors to provide some hysterisis. I also stuck a Red LED which lights up when Backup Audio is enabled.
The right hand chip has 4 op amps and I use three of them (1 for amp and 2 for comparators). The left had chip has the 4 analog switches.