I just discovered an app for mac that uses the Audio Input of the computer and the AD-converter in the sound card as an Oscilloscope.
First, I was thinking this can't work... but theoretically, it's a great idea! I know it can only measure for frequencies starting from ~20 kHz, but if you need to measure MHz, then it's just fine.
my question is: How reliable is this technique, independent form the Software? If you build a nice adaptor with overvoltage protection (max 2V), then I suppose there is no danger for the sound card on the computer, right? Any other experiences?