lillo9546 The microphone jack only detects up to 22 KHz and won't tell how strong the flicker is due to the lack of any scale. You need a real oscilloscope - probably any would do that has a decent sample rate. Rule of thumb is, if I remember correctly, to have at least twice the frequency of the flicker (in Hz) one wants to measure as sample rate.
I have never heard of the oscilloscope you linked to, and am surprised to see it is available for 30 Eur and advertised as having 12 bit accuracy. Normally such high accuracy oscilloscopes are pretty expensive. For example, the 12 bit PicoScope USB oscilloscope lists as over $800.
I don't know if it will work. I'm no electronics guy either though - I just kept trying things until they worked (as seen in the oscilloscope thread).
I'm not sure how the limited bandwidth (200 KHz) will come into play.
If it works, it is the cheapest solution yet.