I recently built my own Eurorack module. It was a long and detailed process, but in the end, the reward was well worth it! The goal of this series of articles is to share with the curious DIYer the things I've learned along the way, things that I've found helpful and useful. I will also stress that this is by no means a professional guide to making modules; I am not a professional. Rather, this is a collection of wisdom, things I picked up along the way, things that are good to know.
Without further ado, our first article in this series talks about having a good knowledge of circuits before starting out.
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Part 0: Circuits Background
It goes without saying, but a good understanding of circuits and circuit design is essential for making your own module. You don't need to be an expert, you just need to be knowledgeable about things like components and how to make designs using them. For example, what goes into making a passive versus active filter.
In my case, prior to ever thinking about designing my own Eurorack module, I had a general interest in circuity; analog circuits to be specific. In fact, I had begun self-studying analog circuits shortly after getting into modular synthesis. Not a long time though, only about two years. For me, I was attracted to the idea that some of the best sounds in modular synthesis came from purely analog modules, some designed years before the digital age.
My self-study of analog circuits was in the form of reading textbooks and working through the problems posed in them. One that I can recommend very highly is "Microelectronic Circuits by Sedra and Smith" (I have the 6th edition, but there are newer ones). In my opinion, this is a great textbook for those who want to delve deep into analogy circuitry. Despite being a university-level textbook, it does a great job of explaining concepts concisely and only assumes a very basic understanding of circuits, mathematics and physics.
The book is packed with content, enough for two semesters of study, the authors note. It begins with a general introduction, before making a deep dive into analog components such as amplifiers, op-amps, semiconductors, MOSFETs and BJTs, and the physics behind them all. The later part of the book gets into circuit design/analysis and also touches on digital circuits and logic, for those interested. Throughout the book, various smaller circuit designs relevant to each topic are presented and worked through to provide a deeper understanding of how various components all work together.
Each chapter also has tons of practice questions at the end of it. What's neat as well, and extremely useful for module design, is that several questions in each chapter are labelled as "design" questions. These questions put you in the role of a "circuit designer" and ask you to do things like create circuits, pick component values, etc., based on specs provided in the question.
Once you feel comfortable with your knowledge of circuitry, another tip I can give is to start looking at existing schematics out there for DIY modules. Not really for inspiration per se, but just to see how things are laid out and if you can, in a general sense, understand what's going on. I wrote an article a few years ago about resources for DIY Euroracking (building rather than designing), where I featured two great builders: Sam Battle of Look Mum No Computer and Niklas Ronnberg. Both offer schematics on their websites for DIY builds and I've built a few of their modules. What's cool about Sam's channel/website is that he usually has a YouTube video to accompany each module, where he breaks down the circuit and explains what each module does. Super valuable for people starting out.
Having this background knowledge of circuit design is the key foundation for making your own Eurorack modules. In my experience, it is the part that takes the longest, but is also the most rewarding. I should also stress that my path to studying circuity is by no means the only way, or even the best way. There are tons of resources available both in print and online to aid in your studies. It's just a matter of finding what works best for you and developing that knowledge.
So, you've learned what there is to learn about circuitry and you feel like you can tackle creating your own module, what's the next step? Stay tuned for our next article.
-Uncle Peter
