Seventh Class, The Operational Amplifier

After the typical round of questions and doubts, we have continued with our coursework through the circuits, its elements and methods of analysing them.

We have been introduced to a new circuit element: the Operational Amplifier, aka O-Amp or OA. There are several types of OA's, but the most common one is the one which has 8 pins, each of them dedicated to a specified function: output terminal, negative and positive polarization terminals and inversor and non-inversor input terminals. Its circuital representation is an equilateral triangle with the output in its top vertex. 

Within the first moments of its presentation, you may think that it requires a high level of maths and circuit knowledge but then you realize that it is much more simple that it seems. This is because of the interesting features of the input terminals: 

• The current that circulates through both of them is the same and is equal to zero. That eases the calculus when establishing the KCL equations at the nodes next to them.   

• The OA presents an interesting property called the virtual short circuit, which equals the voltage at both input terminals of the OA. It's pretty helpful because in order to solve some values that involve the presence of the inverting input terminal, first you can compute the value of the non-inverting terminal which is the same, for instance.