It took me longer than I thought it would, but I finally got a circuit to detect audio output. This is the only way I can tell if the MP3 player is actually playing — the computer will need to turn on the MP3 player and then to set it to play. Anyway, the thing that took a while was doing tests with various capacitors and discharge resistors. I wanted at least 15 seconds of silence before the circuit would indicate silence. In retrospect, I probably should have had the computer handle that, but oh well. It's built now. I also added the LED so I can set the trimpot easier — it might have been a better idea to put in a switch or jumper, but I used a large resistor so the LED only consumes a few milliamps.
The other thing today in audio land was to edit the recording I made the other day and make an MP3. It wasn't too hard although I really have no audio editing software so I had to do it with video stuff. Anyway, it's titled "The Edge Between 15A and 15."
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