Experiments

Wire speaker? Alas, probably not

Experiments — Sat, 03 Feb 2024 23:27:46 GMT

While testing a ø15mm piezo as a speaker, I noticed the stiff connecting copper wire seemed to actually work as acoustic amplifier. In the end, it was probably acting as a transmitter onto a metal plate placed on the desk. Still not fully sure.

Antler first segment, two parallel 50mm piezos

Experiments — Thu, 04 Jan 2024 20:50:07 GMT

Not your common headphones. First test of first segment of an eventual 'tunnel'

Servo test with three winged base

Experiments — Mon, 04 Sep 2023 20:03:32 GMT

Testing the robustness of literally the cheapest servo motors I could find, as I will be using 48 of them eventually. They sound "stuttery", but nicer when run a bit faster. I run them at the lower limit of 5V. I'm also testing laser cut wood pieces in the form of three-winged bases. They will be upside down, suspending petri dishes from wires, eventually.

Cheap Audio Ampflication for Piezo Buzzers: PAM8610 vs TPA3310 vs TDA2030

Experiments — Fri, 11 Aug 2023 17:28:01 GMT

I decided to see how low you can get in costs for amplifiers suitable to drive a piezo buzzer sound installation. Basically you get all sort of digital amplifier ICs soldered on a small board with a basic circuit around.

I am now comparing three boards, based on the PAM8610, TPA3310, TDA2030 chips. After I got a lot of background noise for the PAM8610, I figured that the amplification is actually too high, and compared to the previous test, I no longer use a coil transform to match the impedance better with the piezos. With a direct connection, you no longer get background hissing, but you need to drive the amp higher with the line signal. I run all three at 12V, but the line levels are set differently to better match the capabilities of each board. That is to say, they are not equally powerful at full level.

Here's a comparison of the three boards:

PAM8610 based: two channels, runs off 12V, has through holes for powering, left/right output, and stereo line input. No LED power indicator. Pro: all contacts have grid dimension 2.54mm. Pro: small footprint (and shallow, as there are no heat sinks, I guess it doesn't require them). Pro: Quite strong. Con: Left and right output connections are on opposite sides, which can be inconvenient.
TPA3310 based: two channels, runs off 9 to 24V, has through holes for powering, left/right output, and stereo line input. Medium bright Blue LED power indicator. Pro: Strongest and most balanced sound quality. Con: most expensive one. Con: power and output connectors use grid dimension 7.62mm so you cannot use standard 5.08mm 2-pin terminals. Con: largest form factor.
TDA2030 based: single channel, runs off 6 to 12V, has four input pins for line signal and power, and a screw terminal for the amplified output. Very bright red LED power indicator. There is a small potentiometre that can be used to attenuate the amplification. Without the transform, I ended up having it turned all the way up. Pro: cheapest. Pro: smallest footprint. Pro: comes with screw terminals (can be advantage or disadvantage, depending on your use case). Con: sounded the most muffled in my opinion, with pour high frequency or dynamics reproduction. Con: no mounting holes on the board.

At the end of the video, you can hear again all three in succession, playing the same snippet. Note: volumes have been adjusted to match. The TPA3310 seems to vibrate the glass more, but I think it's a positive indicator for better bass reproduction, whereas the PAM8610 might appear more "neutral" but seems to have stronger distortion (to my ears).

Cheap Audio Ampflication for Piezo Buzzers 1: TDA2030 "Hailege"

Experiments — Thu, 10 Aug 2023 18:20:04 GMT

This is the first one I'm testing which comes at ~2 EUR for a mono channel. The board is described as based on TDA2030. It can run off 6 to 12 V (I am using a 12V power supply), has four input pins for line signal and power, and a screw terminal for the amplified output. There is a small potentiometre that can be used to attenuate the amplification. I ended up having it turned down most of the way.

The amplified signal is fed to a single piezo buzzer using an intermediary transformer coil designed for 100V technique, in this case achieving a better match between the typical output impedance of an audio amplifier (suitable to 4 to 8 Ohms) and the higher impedance of the piezos (around 200 Ohms can be measured at DC).

With the forgiving test sound file of spoken word, the quality seems ok, if you make sure the piezo is not distorting mechanically.

Operate rotary dial switch with servo motor

Experiments — Sat, 05 Aug 2023 17:07:59 GMT

This was a bit of a contrived idea, in order to switch one amplified audio signal among twelve speakers. All in all this solution is much more expensive (and probably error prone) than using a series of mechanical relays, and one would have to come up with a construction to hold servo and dial base together. The dials come only in up to 12 contacts, and I had forgotten that the servo does only 180° and not a full 360°.

Using a fan to put elastically suspended metal sheet into motion

Experiments — Tue, 11 Oct 2022 18:35:19 GMT

Using a low power 5V fan on a relay toggled by a Pi Pico to see how much a sheet of copper suspended in its vicinity will be moved. The effect is subtle, perhaps the elongation is 5-10 mm. The fan is quite silent; one could point it more directly at the sheet.

NuagesPad - step 1 - two views attached to the same model

Experiments — Sun, 18 Sep 2022 10:48:11 GMT

Project to implement a 'padded' version of the Wolkenpumpe live improvisation software interface. NuagesPad is inspired by the idea of Etherpad to assemble multiple players within one virtual space, giving each their own view / perspective.

Tagfalter: biphase-mark based acoustic communication

Experiments — Mon, 30 May 2022 22:18:17 GMT

Transmitting a message from one Pi Zero to another via speaker and microphone, and frequency-keyed modulation based on biphase-mark scheme.

Tagfalter: Spatial identity to timbre experiment

Experiments — Sat, 28 May 2022 22:10:07 GMT

Process of creating a sound installation with autonomous nodes composed of a Pi zero / single speaker channel / one microphone channel. Obtaining spatial identification from repeated impulse response measurements, and translating a set of distances to frequencies (timbre).

FScape Feedback Test

Experiments — Sun, 06 Feb 2022 23:06:11 GMT

Next FScape version 3.14 / Mellite 3.13 will contain new feedback UGens. Here is a test with the feedback loop consisting of a Hilbert transform based frequency shifter and a delay, the shift moving the signal down 30 Hz in each iteration. There is an anti-aliasing high pass filter as well. The input signal is just 10 seconds of microphone signal initially picked up, my voice making some screeching sounds. As the process evolves, some interesting changes in timbre occur, notably some extreme energies are coming down from Nyquist, perhaps due to some ringing or other artefacts. The video has a gap in the middle because the computer would freeze (I suspect it was some problem of the screen recorder). The code is quite experimental, as one has to take care to enable sufficient buffering so that the DSP graph is flowing uninterruptedly.

Comparing performance of Lucre2D (alpha experiment) to Processing on a Pi 4

Experiments — Thu, 20 Jan 2022 21:30:07 GMT

I quickly hacked together a 2D graphics layer for my functional-reactive / dataflow model 'Lucre', with a Processing inspired front API, which allowed me to translate the 'Tree' L-System sketch by Daniel Shiffman. While running smoothly on a laptop, the test on a Pi 4B immediately reveals that my library has hardly usable performance at this stage. First part of the video shows the few-frames-per-second of Lucre2D, followed by the totally smooth animation coming from Processing 3.

Pi Pico capacitive proximity sensor test

Experiments — Wed, 05 Jan 2022 18:36:44 GMT

After giving up on the Pi 4, another attempt with the capsense library of CircuitPython on a Pi Pico. The resistor has a few mega ohms; with the correct threshold (which changes according to environment ...) one gets quite a good reading.

Steiner Chain Moons under Plano-Convex Lens

Experiments — Thu, 09 Dec 2021 21:40:32 GMT

I'm starting to explore the visuality of small 2" round screens covered with a half-dome plano-convex glass lens. Despite low FPS (Pi 4B, code not performance optimised), the animation of moons along a Steiner Chain of size 3 is interesting.

Motorised Spray Bottle Test 210401

Experiments — Thu, 01 Apr 2021 16:41:10 GMT

Second attempt - success! This is now with stronger servos (Jamara Q7 Standard - c. 6 kg force), and minimising sideways force by adding a small wood strip to the trigger. It's a bit messy, so I'll add some plastic sheets to the floor, especially when adding Spirulina to the lichen formula and automatically running the irrigation twice a day 😃

Motorised Spray Bottle Test

Experiments — Fri, 26 Mar 2021 19:10:19 GMT

Following a video I saw on YT about activating a spray bottle with servo motors, I tried to recreate a similar setup. It "kind of" works, but the servos do not perform the full required angle. My guess is, they are simply to weak and thus stop at the point where their force is exhausted. They are super cheap SG90.

Any ideas how to make it work? Should I find another bottle with a less strong spring? Should I get better servos? I'm using a PCA9685 board to create the PWM signals, so I'm a bit worried that I have to stick to the 50 Hz / 1-2ms analog servos, whereas the strong servos are usually digital with other frequency range. Hints welcome!

ScalaCollider.js - running scsynth and ScalaCollider alongside in the browser

Experiments — Sun, 03 Jan 2021 18:09:50 GMT

After building the SuperCollider server (scsynth) as a WebAssembly binary for the browser, the other piece that is missing is a full-fledged client to talk to it. ScalaCollider is a client written in Scala that normally runs on the JVM, but it can also be compiled for the browser, outputting JavaScript code. The demo shows how scsynth(.wasm) is controlled by ScalaCollider(.js) inside the browser.

Source code: https://github.com/Sciss/SoundProcessesJSTest

scsynth.wasm (SuperCollider server on WebAssembly)

Experiments — Wed, 30 Dec 2020 20:35:17 GMT

SuperCollider server (scsynth) can now be compiled to WebAssembly (wasm) via Emscripten. Video shows booting of server, loading a synth def, starting a synth, and adjusting one of its frequency parameters. Current development: https://github.com/Sciss/supercollider/tree/wasm

Current README: https://github.com/Sciss/supercollider/blob/0adb2b70484b460872fc830f7a3deffaf1313ab8/README_WASM.md

negatum-864a4fe-opt-par-play200719b

Experiments — Sun, 19 Jul 2020 12:11:52 GMT

Sound synthesis programs found through genetic programming have gone through an 'optimisation' stage that removes redundant elements, then through a 'parametrise' stage that identifies up to five constants that, when modulated, yield clearly different sonic characteristics. Ranges are estimated for these parameters, and input is normalised to the interval [0, 1]; a simple UI can be used to explore these parameters. The next task is to understand how the parameters can be coupled and automatically modulated by other processes, while still remaining within interesting sonic spaces.

(another go, this time showing the right source code)

negatum-864a4fe-opt-par-play200719

Experiments — Sun, 19 Jul 2020 11:37:05 GMT