The third book in the series (electronic) "Schematics". The focus is on the 741 Opamp, comparator circuits, electronic switches sensitive (e.g.) for light or temperature, squarewave generators, the 555 (timer) chip, the Schmitt trigger, High Voltage generators, an elementary oscilloscope circuit, analog timers, relay circuits, The book is written in English. (107 pages, 25 pictures, 65 schematics). Copyrighted content.