anb2020:
I guess nobody knows how to solve it : (
Turn that frown upside down! There are pages and pages of op-amp instruction on the web. The 1st result I clicked on provided a very important clue in re. that circuit diagram.
Osgeld:
its not that hard, and its not a transistor
From the drawing: 'All steps must be based on knowledge that we all know through mechatronics or before.' Hmmm, doesn't look like a Transformer either. 