Many people think that to switch from analogical signal to digital one is easy, but most of the time it is so difficult that you must use a converter.
AZEskop is an analog-to-digital converter. In fact it is a low-frequency oscilloscope which uses your sound card as a converter. It uses two channels. You can use the following combinations: Ch1+Ch2, Ch1-Ch2, Ch2-Ch1, - Ch1 and - Ch2. You can save your work to BMP, PNG or JPG. When saving, you can use sample-time and backups can be viewed by the built-in viewer.
It has a pleasant graphics interface and data reading is easy. Its use requires nevertheless knowledge in electronics and physics.