[Lab02] Some notes on Inverter, Theory, and Reality 이론과 실제의 간극, 그리고 인버터의 이모저모

The experiments I’m introducing were conducted about three years ago, so the vividness of those moments might have faded a little. However, the most valuable discovery from that time was not just the fact that I completed the circuits, but that I got a true taste of the gap between theory and reality.

Typically, when creating variations in a circuit, the first element people look to is the resistor. I’ve previously shown examples using a xylophone as a resistive body. However, the most interesting harvest from this experiment (perhaps felt more strongly due to my lack of prior knowledge) was the change that occurred when swapping various capacitors.

Various Capacitors

In reality, there are so many different types of capacitors. Depending on their material and construction (polarized or not, degree of stability, etc.), and how they are connected, the dynamics of the circuit change significantly. The calculated values in an RC circuit are actually quite abstract figures; in a real-world environment, staying exactly at those numbers requires immense effort to prevent noise. For me, however, that discrepancy is exciting. As long as basic operation is guaranteed, all these unpredictabilities become meaningful.

While a change in resistance directly alters the frequency by slowing the flow of current, the capacitor not only sympathizes with that process but also becomes a key element in determining the timbre. Even with the same capacity, using a capacitor made of a different material changes the texture because the capacitor itself acts as a kind of filter. For those of us who handle circuits as musical material, this is an indispensable element.

Another thing that awakened my naivety was the role of feedback. My previous experience with feedback was primarily positive feedback in audio signals—a phenomenon where a specific frequency explodes and reinforces itself. Because I had focused mostly on unwanted howling or chaotic instability, adapting to the completely different nature of feedback found within a circuit was quite challenging. I wondered, “How can feedback create stability?” Believing that feedback always symbolized instability was a very one-dimensional thought.

Feedback in a circuit mainly takes the form of negative feedback, where the output suppresses the input. The structure of an inverter oscillator utilizes this very principle. By returning the output to the input to constantly flip the state, with the speed controlled by R and C, a steady oscillation is created. In other words, feedback here serves as a stabilizer that sustains the oscillation while keeping the system within a specific orbit. The diagram below shows an abstract form of feedback without R and C.

In the previous 4049 inverter experiment, I used ceramic capacitors to allow the voltage to swing between two points. When used to ‘copy’ and return a signal from a specific point, these are sometimes called ‘feedback capacitors.’ Since the 4049 lacks hysteresis, the transition between 0 and 1 is extremely sensitive and unstable. The numerous noises generated during this process mix into the output, which, from a tinkering perspective, becomes very interesting musical material. On the other hand, a Schmitt Trigger filters out such ambiguous noise sharply, making it more suitable for clean oscillator design rather than experimental purposes.

Furthermore, the 4049 has a random distribution of Vss and Vdd for each input, making the starting point difficult to predict. Without an initial connection, the voltage maintains a random value; the moment a connection is made, it starts operating from an already random voltage level. It’s a truly thrilling point.

A few more notes on inverters:

A series of inverters can create a delay, influenced by two main factors:

  1. Capacitor values: Capacitor Delay
  2. Gate latencies: Connecting an odd number of inverters in series is called a “ring oscillator.” A minute amount of time, measured in nanoseconds, is required for the signal to pass through each gate, depending on the IC chip’s design. Gate Latency

Note that an odd number of inverters must be connected for oscillation to occur. If an even number is connected, the output becomes latched to the same state as the input, and the circuit stays in one state without oscillating. Even Number Latch

To create a distinct time delay audible to the ear in an analog circuit, a separate “clock” device is required. The gate latency method described above is closer to a phase shifter that subtly pushes the phase of the waveform, rather than a traditional delay, as it operates on a fleeting nanosecond scale.

[Signal 01] Entrance Exams: What the Rejection Letters Taught Me / 입시, 그 실패들이 내게 가르쳐준 것들

MIDI Studio, Institute of Sonology in 2006. Now this studio does not exist.

I spent a long time contemplating how to title this piece. In Korean, I wanted to focus on the theme of ‘Ipsi’ (Entrance Exams), but simply translating it as ‘Entrance Exam’ in English felt like it didn’t quite capture the full depth of what I wanted to convey. Regardless, I’ll begin the story here.

April is the peak of the entrance exam season for Dutch music conservatories. Students usually finalize their career paths and begin submitting applications as early as February. By March, the number of applicants is tallied and professors begin carefully reviewing portfolios. In April, results for Master’s applicants are typically released first, while Bachelor’s applicants wait a little longer.

Looking at my meticulously organized (?) life now, people might assume I was always a model student. However, those who have known me for a long time know that I had a complete “reformation” about 30 years ago. Before that, I was, quite literally, a troublemaker.

To talk about entrance exams, I must disclose this past. The core of those “unexplained long years” was the process of playing catch-up with my studies. During high school, I was interested in nothing except satisfying my curiosity. I loved music and had many dreams, but I poured all my energy into dating, band activities, dancing (don’t be shocked—I used to be a cheerleader), and composition. I was completely immersed in my own world of being a ‘performer.’ It wasn’t that I hated studying, but by the time I took it seriously, it was already late. Even now, remnants of that time linger within me. I may have been born with a gift for improvisation, but I might not be a natural-born strategist. There’s a bit of that in my works as well; I only realized this after turning 35, and I am still striving to overcome these shortcomings.

Going back to my high school years, I was completely unprepared for entrance exams by the time I graduated. As a result, I had to spend two long years—what we call Jaesu and Samsu in Korea—making up for lost time. Looking back, my second year of trying (Jaesu) was quite interesting, mostly because I was still more interested in the social scene and hadn’t quite “woken up” yet. However, shortly after starting my third attempt (Samsu), the joy of studying began to slowly creep in. Every human certainly has their own “time.”

During that third year, I raised my CSAT (Suneung) score by about 50 points. I applied to three universities and barely got into my second choice. Once in university, I fell deeply in love with studying. I stayed on a scholarship for all four years and entered a life as a ‘model student’—something unimaginable in high school. My curiosity hadn’t diminished; it had simply shifted its focus toward academic study and creation.

What I really wanted to highlight here is the fact that during those three years of entrance exams, I submitted applications to nine different universities, only to be accepted by one. After successfully completing my undergraduate studies (for the record, I didn’t just graduate at the top of my department, but was the overall valedictorian of the entire university and received the Presidential Award. Ha…), I started studying electronic music with a determination to study further. (I’ll save that story for another post.) However, I couldn’t find a place in Korea that truly called to me, so I decided to go abroad and threw myself into studying English.

Although my English score on the CSAT was high, I had never actually had a conversation in English. So, for about two years, I set music aside (except for piano practice) and focused entirely on the language. Then, I headed to Canada. My only thought was to get out of the country and accelerate my English studies. I am deeply grateful to my parents for allowing and supporting this. That marked the beginning of my first overseas venture for about a year and a half. Canada was freezing, but my English studies were quite successful. I did nothing but study.

While there, I also prepared for entrance exams for American universities. I took the TOEFL so many times I can’t even remember the count, and I began studying for the GRE. I sent applications to over 20 schools across the US and Canada. The results were catastrophic. For someone who had been thriving and immersed in studies since entering university, this was an immense despair. I didn’t hear back from a single place. I didn’t even pass the first round. I tried to shift the blame away from myself, telling myself it was because I hadn’t used an admissions agency, but the truth was that I was simply, absolutely unprepared.

Panic-stricken, I eventually packed everything up and returned to Korea. That year and a half in Canada wasn’t a short time, and my first experience living abroad had changed me significantly. The way of thinking, the cultural differences, the widened perspective… I know now that none of those experiences were in vain. But back then, I couldn’t see that. I felt a deep sense of depression for the first time in my life, and I had gained 7kg.

I decided to set everything right and regained my resolve. Returning to my roots, I pulled all-nighters at the library, balancing exercise and study. I studied English again and worked on new pieces to strengthen my portfolio. Each day felt urgent, and at the same time, I was happy.

As winter was fading, someone suggested I apply to the Institute of Sonology in the Netherlands. Since I had originally aimed for the US, I didn’t put much pressure on this application. Perhaps that lack of tension is what led me there. That single application changed my life entirely. Now, 20 years later, I am still here in The Hague, teaching students at that very institute.

Entrance exams place your life at a crossroads. It’s a major decision, usually made in one’s youth, that determines the direction of a life, and the effort required is immense. The weight of it is an experience that can only be felt at that specific time. However, the meaning of the result is quite different from how it feels in the moment. Whether a door opens or closes isn’t entirely up to me. While the result says something about my current state, it is by no means an absolute standard of evaluation. The entrance exam is not a process that provides a neat answer to your skills and level like a mathematical formula.

It’s hard to see it then, but looking back, those numerous failures led me to a place where I could grow significantly—artistically, intellectually, and spiritually. I am sincerely grateful for each and every failure that began with my university entrance exams. And I am grateful that the fire that started burning inside me after those failures hasn’t gone out in the 20 years since.

So, I want to say that the experience of an entrance exam is incredibly precious, regardless of the result. It might not be a joyful event where you can enjoy every moment, but it is an opportunity to have parts of yourself objectively evaluated. Recognizing that this evaluation isn’t absolute becomes a great milestone in life. I want to tell all students that the result is not an absolute indicator of success or failure, but rather a great opportunity to look deep into one’s own heart. As time passes, all that effort becomes a beautiful memory. I want to say thank you once again to all my failures and rejection letters.

[Signal 00] Introduc…tion

I mentioned that I’m preparing three or four different series, didn’t I? If you ask why I’ve suddenly started writing like this; well, I’ve actually written a lot over the years, but my primary reason now is that I’ve decided to write things that can be shared, rather than just keeping them to myself. I wanted to write freely about the books I read, the space I live in, the work I do, and my own thoughts.

That said, I can’t just write absolutely anything. I figured that organizing my writing into three (or perhaps four) major frameworks would make the process smoother, keep the content balanced, and perhaps even broaden my own perspective.

Above all, I have always loved writing. Even during my school years, I was constantly writing something. I thought it would be wonderful if I could take that thing I love and, with the help of a bit of a “system,” turn it into a medium, aside from music, that I can share with others.

There are moments while reading a book when you feel a sudden urge to write. There are certain authors who evoke that. Perhaps writing is a way of recording the intensive thoughts one has at a specific moment (unless one is writing a novel, though even novels, in a broader sense, reflect the author’s thoughts at the time). Some of the humble posts I’ve uploaded to this blog date back more than 20 years. What I am truly grateful for is that, looking back at those “insignificant” entries, I can re-read exactly what I was thinking two decades ago. This is a privilege reserved only for those who write. To be able to see my own thoughts from 20 years ago—how many people in the world actually get to preserve such moments?

What I was doing back then is important, of course. But tracking the evolution of my thoughts is truly vital. I am such a different person now than I was then, and I know that I will continue to change.

In any case, that is why I intend to keep posting. This “Signal” series will be an attempt to consciously draw connections between my life in the Netherlands and my work or music. My daily life acts as a signal for my work, and my work, in turn, sends signals back to my life.

While the “Lab” series will cover the trials and errors occurring within my studio, “Signal” will be about the stories happening outside of it.

Ah, my blog is quite old, so the categories don’t always organize themselves very well. Nevertheless, I trust that if there are long-time readers still around, they will navigate through them without much trouble.

And to anyone who takes the time to read this, thank you so much.

Image by Shutterstock.