# How to understand circuits

Hello, i'm in my 2nd year of EE. I have done circuit analysis and some basic into to diodes, transistors and op-amps.

We have a class in which we are given circuits for a audio amplifier and a power supply. We are required to understand the circuits completely. How they work and why each component is necessary.

I am not sure how to approach this. I have learned how to calculate voltages, currents etc. But not design. Is this common in universities? My understanding of semiconductors is weak so i am going over op-amps and diodes again.

How can I learn to understand circuits?

UltrafastPED
Gold Member
The first circuits course is usually analysis ... how to understand what is going on ... and you focus on solving for the currents and voltages, starting with static cases using Ohm's law and KVL/KCL (batteries, power supplies, resistors, some diodes and transistors, op amps), then transient cases using Laplace transforms (switches), then alternating currents (fixed frequency, phasors, power transfer).

During this process you will start to recognize certain standard elements: voltage dividers, bridges, rectifiers, simple filters, etc. Design is the process of putting together these elements to achieve a particular goal. This is very similar to how you learn computer programming: you learn a language, its syntax and objects, then you write programs which do what you want.

Typically your second class will be a systems and signals course for linear systems; then you will learn how you can design analog systems starting from the abstract goals - this is a fairly mathematical course, but you will learn a lot. If it is a good course there will be labs where you build circuits which illustrate the theory; usually these will be radio circuits.

The real design work comes as you take further courses where you will learn how to think about transistor logic, power systems, and controls. In the meantime you can move ahead on your own by learning more about basic circuit elements, and building stuff yourself. Lots of practice with a good SPICE program is also useful ... then you can simulate your designs prior to doing a breadboard.

AlephZero