# Electronics Calculations Data Handbook

Back in 1997, I was doing a lot of freelance design work, almost all analogue audio stuff. Over a period of time I noticed myself doing the same basic types of calculations over and over; calculating CR time constants, things like that.

A lot of what I designed I ended up testing as well, as much of what I did was only built in small quantities. When I checked things, it always irritated me if the gain through every board was, say, -0.5dB when it should be 0dB. The difference is small, and usually doesn't matter in practice, but I didn't see why things shouldn’t be as close to perfect as possible.

The way things work out, these small errors are usually down to the range of components that are commonly stocked. Resistors, capacitors and so on come in certain fixed values, known as the E12 and E24 series (the most common ones). That means that for E24, there would be 24 standard values between (for instance), 100 and 1000 ohms - in each decade.

Most of the commonly used design equations are quite simple - products, ratios and so on, and often I found myself trying different combinations of E24 values trying to achieve a certain ration. This trial-and-error thing also irritated me (yes, I am a bit of a perfectionist). So in my spare time, I started doing some programming to compile tables to make these tasks easier.

Now, in those days, I didn't even have a home PC. At work, I did most design work with pencil and paper - I drew circuits by hand and sent them to a PCB designer for layout. But I had done some programming, mostly in BASIC. Using first a PC that my father used, I started compiling tables. The program computed all the possible values of the various combinations, and then sorted the results. With all possible values arranged in order, it became much easier to see the possibilities in a certain design situation.

I thought that this was innovative and useful, so I approached several technical and academic publishers. After a while, I found myself having lunch with a nice man from Butterworth-Heinemann, who liked the idea. (This led to me, eventually, buying my first computer of my own.)

They also asked me to provide some other material to go with the numerical tables. So the first part of the book is my attempt to explain the fundamentals of electric circuits. I&rquo;m not sure how well I did with it, but I enjoyed the challenge. there is nothing like trying to explain something in a simple and clear way to clarify your own understanding of a subject.

Writing the book took me about three months I think. As well as the tables and text, there were also a number of hand-drawn figures.

The book is still around, and you can now buy it as a Kindle e-book, even. I still have one of my original copies. I do still find it a useful design aid on occasion. And I am proud to have something in print which is, I hope, useful to technicians and engineers.