Same signal, many sounds by kelly heaton

I've been migrating my circuits out of the breadboard and into soldered form. I'm also hooking up speakers so that my sound generating circuits are ready for installation in a sculpture of Virginia's nocturnal ecosystem. Because most of my circuits use a custom piezo electric speaker (built with my own amplifier board), I have to install each piezo element into a physical housing... and there's some interesting "play" here. One electronic signal can generate many different sounds depending upon the speaker's physical design. Here's a video of me testing various installations of a piezo element for an insect that makes a steady background noise.

It's cool to experiment with the interface between electrical signal and material properties. It's also critical to get it right, or else the piezo element will make a horrible rattling or screeching. Even a tiny drop of glue (to fix the piezo element in place) will alter the sound quality --usually the pitch-- and superglue can sound different from rubber cement or hot glue or tape. All of this is no news to a human musician, who knows that a note ill-played (even slightly) is a fail, and teensy subtleties often make the difference between average sound quality and genius.

It is interesting to wonder what makes animals of the same species sound different in nature: is it their electrical impulse or their physical form? (Is it their schematic, their CAD file, or their bill of materials?) Members of the same species inherit the same circuit design as well as physique. External physical factors, such as climate, have some degree of influence over material properties of the body --for example, a dehydrated cricket sounds differently than the same cricket wet with rain; a fat frog sings a different tune than the same frog skinny; and so on and so forth. We also know that "animal circuits" are sensitive to electromagnetic fields, and capacitive coupling undoubtedly affects individuals in close proximity. I suspect that physical factors play a greater role in the variability of an individual's song if but for no other reason because birds sound the same whether they are sitting on a tree branch or an electrical transformer (at least, I think they do). PS: Eventually I will tackle the challenge of bird song, but their vocal complexity requires more computation... which is why I have started with insects.

To end this log, I leave you with one more video clip of my "background noise" insect. Here it is with a plastic spool installed over the piezo (now painted green, black, and white). The soldered perfboard is embedded in a cardboard cutout that is painted to look like a forest creature sounds. Soon, this mixed media object will be joined with other embellished animal circuits to build a vignette of nocturnal musicians.

lesser angle-winged katydid by kelly heaton


Watercolor and analog electronic study of a Lesser Angle-winged Katydid, 2018. I plugged in a couple of crickets to give this fellow some natural context. To read more about how I made this, visit my project “Hacking Nature’s Musicians” : https://hackaday.io/project/161443-hacking-natures-musicians

Follow me on Hackaday by kelly heaton

I have started a project to describe and share my analog electronic circuits designs so that people can better understand my electronic practice. My project, located on Hackaday.io, is called “Hacking Nature’s Musicians.” You can find it here: https://hackaday.io/project/161443-hacking-natures-musicians

In a recent project log, I describe how I create chirping crickets using discrete transistors. Check it out: https://hackaday.io/project/161443-hacking-natures-musicians/log/153312-crickets-natures-favorite-astable-multivibrator

Owl surgery by kelly heaton

 Paper owl looking onto its electronic eye circuit, 2018

Paper owl looking onto its electronic eye circuit, 2018

Transitions. Sometimes it feels like the holes that we have are equally -if not more- beautiful than what promises to fill them. Here, a paper owl contemplates the circuit that I designed to fit into its eyes. The addition of electronics to a static object adds more than functionality and aesthetics - it changes the identity of the object. Non-electronic things live in a physical world with thousands of years of creative history, while electronic things are very new. What was once an owl then become a robot - perhaps more robot than owl in our estimation. Does the owl stand to lose more than it gains?

Machine-centric intelligence by kelly heaton

We struggle to relate to machines on their own terms, despite the fact that we created them. I suppose there are people with fluency in some machines, but the body of knowledge in computer science alone vastly exceeds anyone's capacity to understand. Moreover, there are subtle and often surprising effects that arise from even basic electronic components - instruments for manipulating electricity in ways that have yet to be discovered. 

However, if you add human features like the eyes in this video, suddenly we connect. But with what do we relate, really, besides our own reflection? We must push ourselves beyond human-centricity to see things for what they really are.

Shift registers by kelly heaton

I am in the process of building a control system for the insects in my latest Electrolier. As a starting point, I will use shift registers with (or possibly without) linear feedback. Adding linear feedback involves "tapping" two or more of the logical outputs, evaluating their state with boolean logic (usually an XOR gate), and feeding the result back into the start of the shifting sequence. In my video, you can see two 8-bit shift registers in the center (TI part number CD54/74AC164E). I put LEDs on the logic outputs Q0-Q7 to visualize what is happening. As you can see, the LEDs of the two shift registers are not synchronized, a property of an undefined starting state that I will exploit to get randomness for "free" -- at least that's what I'm thinking.

More about my breadboard: on the right is a 555 timer in astable mode which provides a clock pulse of about 1x per second. On the left is a 5 volt regulator - this part is irrelevant if you have the correct DC supply voltage, but mine is 12 VDC.

Good general overview to answer the question “what is a linear feedback shift register” (LFSR):

On choosing taps for a linear feedback shift register:

Mini project on how to implement a LFSR: https://www.slideshare.net/KishoreChandrahasVanam/lfsr

Another helpful paper on using an 8-bit LFSR (i.e. Texas Instruments chip CD54/74AC164):

One final note: because shift registers are comprised of flip flops, an option to add true randomness to this otherwise pseudorandom bit generator is to exploit the metastability characteristics of a flip-flop as described here by @crj11: https://electronics.stackexchange.com/questions/394557/old-school-pseudorandom-pulse-generator-requesting-assistance-with-hardware-des?noredirect=1#comment965703_394557

August insects by kelly heaton

 Landscape painting and analog electronic soundscape (detail of work in-progress). August 2018

Landscape painting and analog electronic soundscape (detail of work in-progress). August 2018

I create the sound of a buzzy August insect using a 555 timer to drive a transistor astable multivibrator (to give timbre). Another slow astable multivibrator provides pulse input to a 555 timer in monostable configuration, that gives a pulse out to the base resistor of an astable multivibrator that sets the tempo. That's why the insect rattles for awhile and then stops (monostable 555 goes high - the rattle tempo is active low).

Prototyping Night Insects by kelly heaton

Here I am at my bench prototyping various analog electronic insects for my latest "electrolier" sculpture. The sounds are made using a combination of astable multivibrators (oscillators), some of which create the audio timber and others establish a chirp-like tempo. The speakers are custom piezo electric devices that I have physically modified to achieve different sound qualities, such as brighter versus muffled and close versus distant. Individuality is achieved by subtle variations in the electrical signal and the output device.