Curious Cube
Feb 3 - Mar 10
What is it?
QQQ is a soft musical interface. From outside, it’s an adorable, fluffy cube, but the “inner part” is a little evil. It will make unpleasant noise when you move it around.
With a strap, it could also be a wearable instrument that considers the body as the “wall”.
Inspiration
The inspiration came from the world’s first electronic instrument—the Theremin. I did a prototype Theremin experiment in my pcomp class last semester, and I also wanted to make a soft instrument. So a simple idea came up: use two proximity sensors on the front and side faces of the cube. If you place the cube into an open box, the two sensors can detect the (x, y) position and make different sounds based on the distance from the walls.
555 Timer
Another thing I wanted to experiment with is analog circuits. I used two 555 timers in my circuit and two IR sensors that control the pitch and the tempo. The first sensor that came to my mind was the ToF sensor, which is a digital sensor, not an analog sensor. So I pivoted to an IR sensor because it outputs analog data. You can consider it a variable voltage.
Pin 5 on the 555 timer is the control voltage pin. I connected the Vo pin (voltage output) of the IR sensor to Pin 5 (you can check this in my schematic). To connect the two 555 timers, I connected one timer’s reset pin (Pin 4) to the other timer’s output pin (Pin 3).
IR Sensor
In my first test (using a single 555 for tempo change), I found the result to be less obvious for tempo changes (I should have tested pitch first), which slowed me down quite a bit. I read the datasheet of the GP2Y0A41SK0F, a short-range IR sensor. After that, I started to add the pitch part into my circuit, and it turned out that the pitch change is much more obvious compared to tempo, which made me happy.
Besides building the circuit, I observed something interesting: both pitch and tempo are not linear when I move the cube linearly. I looked at the datasheet again and found that the output voltage follows a curve, with a peak at 4 cm. So one of the tasks I asked the class to do was to find its lowest and slowest position. The answer is obvious if you look at the datasheet—it’s 4 cm by 4 cm.
Enclosure Design
I’ve always wanted to combine my hobbies with my professional practice, and I finally decided to do that in this project. I had the idea of making a soft instrument last semester, but it was just in my head. In this case, I decided to crochet the cover of my 3D-printed enclosure, which can also be considered the solid structure.
The first cube I made had less consideration. I didn’t think about the mounting parts for both the speaker and the IR sensors, and honestly, it was a little too big. I wanted it to be as compact as possible. So I learned how to model and print a single test part for the cube so that I didn’t have to wait 12 hours to print a full cube just to see if the components would fit. But things happened anyway. It turned out that the test part was printed upright, but in the actual cube case it is the facade, so it condensed a little bit because of gravity. It still worked with screws—or maybe even better—but it wasn’t what I expected.
My next step is to add a switch to the circuit so that I don’t have to open the cube and plug in the battery every time I want to show people this project. Or maybe I should also use a motion detection sensor. Then whenever you move the cube, it will make noisy sounds! :)))) FUN!