OPERATIONAL AMPLIFIERS AND OTHER SPECIAL DEVICES concludes this «Trilogy of Electricity» with a book that not only continues with the line of the previous two texts, but complements what could be called a specialization in the field of electricity and electronics, and electric and electronic circuits. In this third volume, the protagonist element is the Integrated Circuit (IC), and especially the Operational Amplifiers and the 555 Timer. With these two ICs, and the incomparable help of other special devices that the author also deals with and analyzes, such as the family of so-called thyristors (SCR or Silicon Controlled Rectifier, TRIAC or Double-Sided Triode, DIAC, CUADRAC, etc.), the author helps the reader understand the usefulness of their application: comparators, sine wave to square wave converters, summing amplifiers, integrators, differentiators, logarithmic amplifiers, antilogarithmic amplifiers, waveform converters, etc. As always, diagrams, formulas, graphs, solved and proposed exercises. A whole amalgam of knowledge to make the interested reader always feel accompanied.