trying to help a developer (Ben Levitt) to track down a bug on my UavDevBoard system, it was hard to explain by email the strange behavior.
After he suggested me to try with a sound card oscilloscope, I decided to try something I was planning from sometime now : a soundcard oscilloscope.
I build a voltage divider to scale down PWM voltage (3.3V) to about 0.7V, which is more suitable for a PC audio input.
I crimped a couple of cables with servo connectors on one side and a stereo mini jack, from a boken headphone on the other side.
The interface is double channel capable, but some PC (like my laptop) only has mono input.
On the picture above you can see a double channel PWM signal from two different UavDevBoard outputs.
Here you can find a little tutorial, with schematics and pictures, I did about all that.