Screen shots from a PCB that I’m designing — an analog electronic bird song generator with a primitive interface for adjusting the song, aka “patch bird.”
song
Analog electronic warbler experiment /
This analog electronic birdsong generator circuit is comprised of 5 transistor oscillators, several passive filters, and an audio transformer “voice” generator.
Pretty Bird ver. CC 2019 /
Here it is at last: my edition of 150 printed circuit boards and associated components, “Pretty Bird ver. CC,” 2019. This multiple was commissioned by Creative Capital for their 20th summer retreat celebration. I designed the artistic circuit using discrete hardware to generate waveforms from a 12 volt DC power supply, visible as blinking LEDs and audible through an 8 ohm speaker. Under the right lighting conditions, the sound is reminiscent of “pretty bird,” a song of the Carolia wren. There are no audio recordings or software algorithms involved in this effect — it’s entirely analog electronic. In the upper left corner of the circuit is a light-dependent resistor that affects the frequency of a negator oscillator, as I demonstrate in the video by changing the ambient light. It’s fascinating to me that a small quantity of common transistors, resistors, capacitors, and diodes can create vibrations that are so life-like. Similarity or simulacrum? The spark of life.
life-like bird song circuit /
This simple circuit sings like a bird, even with chirp variation! This effect is caused by various discrete non-linear components in a breadboard. I tried to build a soldered version and, while it sings, I haven’t been able to reproduce the life-like quality of this circuit (hence my theory that parasitic capacitance is at play).
In the front half of the breadboard, you see three astable multivibrators that create an irregular tempo. These are connected back to various locations in a “chirp generator” circuit (based on the classic doorbell canary design with an audio transformer).
New bird in town /
I've temporarily relocated the physical form of Hacking Nature's Musicians to the other-worldly environment of Tortuga Escondida (near Akumal, Mexico) for a one-month fellowship on los musicos de la selva. Thankfully, my supplies made it through airport security and there's air conditioning to protect my electronic equipment against jungle humidity. Here's a photo of my bench showing a view of the jungle canopy and stairs to a roof deck with an amazing panorama over the electrically-charged ecosystem. (Giant scorpions occasionally grace my window screens but I have spared you that visual discomfort.)
My electronics bench at Tortuga Escondida near Akumal, Mexico. October, 2018
A few observations before I jump into the main content of this log: (1) Tortuga Escondida seriously resembles a research facility from the TV series Lost, so if I disappear you know what happened to me; and (2) the insects here are at least twice the size of their Virginian counterparts. Check out this insane Katydid!
Amazing giant Katydid in the jungle around Tortuga Escondida (greater Akumal, Mexico). October, 2018
Amazing as the insects are, I'm not studying musical bugs because what's most remarkable to me --coming here from Virginia-- are the myriad species of birds. I've decided to see what I can do with the analog electrical engineering of bird song.
As a starting point, I built a version of the classic, "chirping canary" used in kitschy artificial nature scenes. Check out my files on Hackaday.io for an annotated version of this schematic, which is based on audio transformer oscillation. Basically, the surge in DC power that happens when you first turn the circuit on is capacitively coupled across the transformer and continues to fluctuate thanks to a transistor switch. If you change (or remove) certain capacitor values, the circuit stops oscillating and makes an unpleasant tone that can be very loud due to the current gain across the transformer.
I've made a first informal video showing how the sound changes when different parts of the circuit are modified (apologies in advanced for some unpleasant beeps - don't wear headphones).
Next, I built a few astable multivibrators and connected them to various aspects of the sound-generating circuit in order to make the chirp sound more like a bird song. Some of my tests are documented in a second video that you can watch on Vimeo.
Watch the green LEDs (and follow the white wires) to get a sense for what the astable multivibrators are doing.
Birds are very clever singer-songwriters, so it's going to take a lot more work on tempo and pitch variation to get interesting songs. I plan to try numerous strategies to generate voice quality because I want to build a jungle of different bird circuits ranging from sparrows to whippoorwills to parrots to owls to a Resplendent Quetzal, relative of the legendary Mayan Plumed Serpent. If you have suggestions for circuits to try, I would be grateful.
So... not only do my bird electronics need work, I could use a new "avian speaker" design. It seems that piezo buzzers are better suited to insects, while 8 ohm speakers have higher bird fidelity. Initially, this observation puzzled me (and I'm still not clear) but I got some useful clues from the ingenious musician, Nicolas Bras. It's material physics: the thin, metal vibrations of a piezo disk have more in common with the chitin instrumentation of an invertebrate than the fleshy air bladder and vocal chords of a squawking bird. Some insects do force air through a membrane, like living kazoos, but crickets rely heavily on the idiophonic effects of leg or wing rubbing. The sound made by an idiophone is quite different than that of an aerophone or membranophone, like hitting a cymbal versus blowing through a reed, the latter of which happens when a bird forces air through its vocal cords. I searched the web for homemade instruments that behave like an aerophone with a membrane and found this cool "membranophone" video by tachionics.
As I did with my "insect-like" piezo, I'd like to build an electronically actuated speaker that has material properties more in common with a bird. I've got various 8 ohm speakers that are working for now, but I suspect that there's a better design to be made -- or at least some cool insights to discover in the process of trying. Again, your suggestions are greatly appreciated!
Stay tuned.
This tarantula was found dead, but I couldn’t resist photographing its exquisite corpse. Impressive creature!
animal: the egg her on song /
Our rooster, Old Crooked Foot, leads his flock of hens in a rhythmic chant to encourage layers.