Designing RC networks is not difficult when you understand how they work. These pages provide the tools for an electronics designer to understand what's going on in a network. They explain what RC networks do, how they work, what the equations mean, and how to design the right RC network for the job.
AC theory was never my favourite subject, and this is not a textbook. I don't mention poles and zeros or the frequency domain. This is more like a series of lectures for practical people who have electronic design problems to solve.

Energy, Phase and Impedance
Mainly about the basics  the differences between resistors and capacitors, phase shift, impedance, the value of (jω), and what RC networks are for.

R and C in series and parallel
The magnitude and phase response curves for the two simplest networks, and how they can easily be sketched as straightline approximations.

Three components
How to design RC networks with two resistors and a capacitor, or two capacitors and a resistor, and how to see quickly what the shape of their response curves will be.

Secondorder networks
The RC low pass filter. How to understand the meaning of a transfer function. The use of Q to describe shape. The bridgedtee notch filter, its limitations, and how to design a steepsided notch filter.
Long ago, back at the dawn of time, when dinosaurs roamed the earth and ladies wore crinolines, I wrote a book on how to design RC networks. It was accepted for publication, but somehow (and I honestly can't remember why) it never actually got printed, though it did somehow get a listing on Amazon!
In the hope that some of the explanations might prove useful to young engineers struggling to understand the craft, I've rewritten most of it, tidied it up, and added some better illustrations. More chapters will appear later, unless I get bored.