Ellie's page on Circuit Bending
always a work in progress.
Table of contents
- Finding Stuff to Bend
- Feedback / Distortion bends
- Pitch Bends and Clocks.
- Power Starve mods
- Picking out Keyboards
- Picking out Toys
- Speakers, 1/4" outputs
Circuit bending has been described by Reed Ghazala as the art of the creative short-circuit. What that means in practice is, taking some piece of electronics - cheap, battery-powered consumer electronics typically - and poking around inside with some wire or alligator clip test leads to cause it to malfunction in an interesting way. This simple description already opens up many doors for the imagination to explore: What is a short-circuit? What is a "malfunction"? Who designs consumer electronics? Where does all of our e-waste go? What are the economic factors at play in production? What ever happened to consumer electronics repair shops? Where is the line between artistic expression and a "derivative work" that constitutes a theft of intellectual property? Are so-called "cheap" and "inferior" electronics actually that bad? How do we decide the value of electronics?.
I became enamored with circuit-bending because of all of these complex and interesting questions that spring to mind. I'll be putting down tons of notes on this page about circuit bending in specific, but i also have a page for all of my various notes on electronics from an outsider perspective.
One Story of Electronics
I grew up just barely at the right time in the 90's to witness the mainstreaming of an aesthetic of transparent cases that displayed electronic components inside of the product. Transparent gameboys, telephones, et cetera. the product itself offering you a window into the fabrication process and tantalizing you with its complexity and ingenuity. A beautiful simulacrum
of this was the cases where some toys or electronics were so comitted to this fad that they made fake circuitry
, sometimes just in the form of a picture of a circuit on a sticker, and affixed it to the product. This aesthetic design choice seems unthinkable in the post-dotcom era of hyper-modernism in which product designers, in their infinite condescension
, see electronic components and circuits as something consumers find ugly, intimidating, overwhelming and so on.
The ironic part of this is that electronics and computing had been core parts of school cirriculum, and an accessible hobby of millions of folks
. As soon as electronic circuits and computers became viable technologies, there was an immediate consensus that they ought to be seen as a part of society's common good
, open and available to everyone. After all, just like the rivers our water comes from, the forests our wood comes from and the air we breathe, electricity
and the various aspects of electrical design such as resistance, capacitance, semiconductance and so on, are all natural resources
that come from the earth and the universe we live in. Nobody really "invented" electronics, they just discovered it; and what is the point of knowledge, science, invention, if it doesn't serve humanity
, but only serves a select few? It was only after a realization by mass industry, ie. via market forces
, that required technical knowledge had to be made artificially scarce
for various reasons. If everyone knows how electronics and computers work, for instance, that puts the enforcement of intellectual property
in the form of proprietary circuits and programs on very shakey grounds, as then all of this it would be common knowledge, and hence un-patentable and unprofitable.
Thus we get the rise of elective, "STEM" education, which is just another layer of irony in this whole story: industry
recognizes that having more people learning about STEM helps them design products, so the feild can't be too
In parallel with Slavoj Zizek's bit about the political aspects of toilet design
, the design of modern consumer electronics may be a symptom of the uneasiness many of us feel about being too intimately confronted with the brute fact of global capitalism's supply chains - and all the moral hazards involved - in the form of visible circuitry, and any noticable vestiges of the manufacturing process, such as visible screws and seams, or anything reminiscent of mechanics. This change in the look of products is accompanied by a change in the way repairs happen (or don't, either out of neglect or for a new-products-only sales strategy). In my neighborhood growing up, there were computer repair shops, TV repair shops, vacuum repair shops, appliance repair shops, and on and on. What slowly took their place was the Best Buy Geek Squad desk, the Target and Walmart returns
counter, and recycling facilities where e-waste
is (supposedly) to be brought to be shipped away and salvaged(?). Just in a matter of years, so much happened. When I was reading my first Dr. Seuss books, the internet, and even computers, were some glitchy, painfully slow novelty. Just a few years later it was something that I spent hours each day using. I point this out, not (entirely) for the sake of cathartic, nostalgic geezer moaning, but to describe how quickly all of these transitions happened...
When we tell a story of short-circuits, I feel obliged to mention this enormous, collective short-circuit that the world went through in terms of technology from about the 80's until the 00's. People who were not alive to see it all happen in front of them... I don't think understand how rapidly so many parts of society changed; how there was no time for any social reckoning with these changes; how they came about, like all technologies, not through some conscious and well-informed democratic decision about bettering our lives, but were heaped onto us by the demands of an incomprehensibly rapidly expanding global economic system.
In a broader note about technology in general, the philosophers Gilles Deleuze and Felix Guattari noted the typical process of technological advancement in their model of nomads and war machines. They wrote a lot of words, but you can pretty much understand it as this: technological and other breakthroughs come about typically from "outsiders" and "nomads", who have a schizoid way of thinking which results in short-circuits that can sometimes lead to enormous breakthroughs. Einstein, for instance, came up with general relativity, likely through a sort of strange mental short-circuit. Einstein himself did not understand the use for his discoveries, but the state, the War Machine, appropriated those breakthroughs and develoed them into weapons like the atom bomb. You can think of tons of other examples of technology being discovered, typically on accident by an outsider who is just experimenting and learning for learning's sake, and then it being picked up by an industry to be appropriated for the purposes of imperialism and capitalism, domination and control and so on.
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Finding stuff to bend
When you are starting out, go with battery-operated stuff
. Do only battery powered stuff for a long time until you are super comfortable and have developed good habits like making sure you know where the power supply is and staying away from it. I honestly don't recommend doing anything else unless you are very careful or have a lot of experience. I had been working on stuff for a few years before i started trying to modify stuff that uses wall adapters
that convert AC 120volts into something smaller like 5v or 9v DC or whatever. I have worked on stuff up to 12 Volts of DC from a wall wart
adapter, and that can shock you pretty bad but its not too dangerous as long as the adapter is working properly.
For the most part you want to look at things that don't use a lot of processing power because stuff that does a lot of processing, tend to use a bunch of digital logic, and require really precise voltages. most stuff that is super digital-heavy also can fry really easily and then be dead forever, because logic voltages are usually like, 1volt, 3.3 volts, or at the MOST 5 volts, but thats rare. so, any wrong move will fry a logic circuit that is hooked up to a microcontroller.
best things to start with are random toys, toy keyboards toy guitars and stuff, another good one is cassette players or battery powered radios
. these arent just beginners stuff, you can get a lot of cool stuff out of those types of things no matter if you are just starting out or have been doing it for a long time.
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as u probly know, the basis for audio synthesizers and well, all sounds in general is oscillators
. here is a secret tho: you can make an oscillator just using feedback. in fact, this is how a lot of oscillators are made, just feedback loops. So, if you know how to put a microphone up to a speaker until it screams, then you know how to make an oscillator, then you know how to make a synthesizer.
literally the first thing i always check
when circuit bending is for feedback
, this you can do by taking the output, wire leading to the speaker +, and running it back into the circuit. if you want to spare the circuit, you can do a bit more safe and use a capacitor of maybe 1uF value, between the speaker+ and wherever you are poking around, but often u dont have to. It also helps to wire up a potentiometer (knob) between the spk+ and whatever you put it into. you may as well, because literally almost everything can do feedback into itself and oscillate. Usually there is a 8-pin chip called the op amp that amplifies the sound. if you want to be careful you can look up the pins in the datasheet of the opamp on what you are bending. but the thing to know is that when you have a active device already putting out sound
and you make it do feedback, you get a weird modulated and distorted
signal. to be breif in explaining, most amplifiers in electronics are made with feedback at very precise amounts, if you increase or decreease the feedback you change the sound's qualities. sometime syou will get just a boring kind of filtered sound, sometimes you will get really weird stuff.
some of the weirdest mind-bending sounds you can get, is if you run the spk+ audio signal through a potentiometer and then back into the clock
, making the output of the device modulate its own pitch. this makes some freakish diarrhea sounds combined which squeeling baby piglets 100% of the time
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pitch and clocks
When you are looking for a pitch bend
, these usually is a result of changing the frequency of a Clock
that controllers a microcontroller. Clocks
for cheap devices are usually made with an RC oscillator (resister+capacitor) or LC (inductor and a capacitor) because this is the cheapest way and fastest in terms of coming up with a design. cheaper things need less frequency stability too (which is funny because you would think that ability to operate despite errors in clock freq would be a positive feature rather than a frowned upon cheap aspect), however if you come across a circuit that is made by a CRYSTAL
, then you might have something that just can not be circuit bent at all. if it is running on a crystal, it probably is really complicated
and often times things running on crystal oscillators only
operate with that specific crystal's frequency, so often times you can not overclock or underclock
a lot of things. SOME things you can, but it is pretty rare, and even then you would have to build a clock circuit yourself, or deal with having fixed crystals selectable with a multiposition switch and all of that is annoying
af to do.
if you see one of these
in what you are circuit bending, you probably won't be able to do much, because this is a crystal oscillator
that operates at a specific fixed frequency.
for CHEAPER, crappy microcontrollers usually operate above 3Mhz
. This high frequency is got by very precise RC or LC circuit values, and very interesting effects happen when you turn that clock way down to the KHz range or less, resulting in not just a "pitched down" effect, but a crazy digital mess. The fact that MCU's run at MHz frequency also mekaes them prone to interference
especially when they are RC-based oscillators, as differing conditions like temperature and interference/noise particularly effect the higher frequencies, because exponential responsiveness - frequncy - harmonics - .....whatever. The Potentiometer
values to use for most clocks is 1M! for when you Simply replace the resistor in the RC circuit with a 1M (or more) potentiometer. Other way to change clock speed is to connect the RC circit to ground (negative/black) thru a potentiometer of 100K-10K, but for me i usually prefer replacing the resistor with a 1M or higher pot. also, if you are feeling adventurous, you can try makin a voltage divider to offset clock frequncy.... because most of the time, higher voltage means slower sounds
im sure there is a smart way of explaining why, but whatever.
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A Note On Power-starve and supply:
a proper power starve glitch should use all three lugs of the potentiometer. Often, if you only use one, the amount of current remains the same and it will burn your potentiometer out, resulting in a somewhat entertaining fire, sizzling and smoke. for a proper undervoltage you will want to have the center lug of a 10k pot hooked up to the positive supply, one of the other side lugs hooked up to the circuit board being powered, and the lug on the opposite end of the pot should be hooked up to a resistor of less than 1Kohm (to limit current so the pot doesnt go on fire, make sure u check the resistors power rating, you might have to use two resistors in series) then to the negative power supply. don't waste your pots!
For better detail, ust look up "voltage divider potentiometer" and see how it is done. the other thing tho is u usually want that extra resistor to ensure you aren't just completely shorting the power supply. If you are working with something running on less than 3 volts, or two batteries, you can sometimes get away with using a 1k pot case the current isn't very much. a lot of commercial guitar effects pedals can be circuit bent by undervoltage, feeding them less power than they need. ive had good results undervoltaging my reverb pedal, resulting in really weird sound garbling.
Also, Look up how to make a voltage divider in general because it will be helpful in letting you be able to power pretty much any device on 9vdc pedal power
supply. If you have something that runs on 4.5 volts (three AA batters), you can use just a simple 10K and 10K resistor to drop the voltage down from 9v supply to 4.5v. theres calculators for how to divide down to different power levels. this is usefl and makes u not have to buy batteries, its also usually safe to circuit bend stuff running on <9vdc even if youre using a wall adapter cause the wall wart has protection in it itself, so if you manage to get hurt from one you must have accidentally reated a voltage/current multiplier which is not likely you would do on accident cause they are really fucking annoying to make.
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everyone talks about the Casio SK-1, and it is a great bend. But don't be decieved because MOST
Casio and Yamaha keyboards are NOT
bend-able or if they are, it is risky and difficult and frustrating as hell. Why is this?
it is because they use a lot of digital logic. And specifically, a lot of what makes them difficult is that the way different sounds are selected, the way the tempo and volume are often control by digital pushbuttons, there is just a lot of digital logic going on that requires really specific sequences of voltages to do things, and a lot of the Yamaha and Casio keyboards are 100% locked in to a specific Clock frequency, the Chips are heavily protected from "malfunctioning" etc. The Casio SK-1 is an exception, probably because it is itself already a weird, kind of experimental keyboard.
This isn't to say it isn't worth it to try to bend keyboards, but my best experiences have been with super cheap toy ones (Kawasaki in particular are almost all awesome to bend, and Kawai) adding pitch bends and stuff. But I just would warn u that they fry easily
as well. So basically, if you are gonna bend a keyboard, be prepared to have just wasted $10-$60.
Things to look out for are if the circuit board has a big MCU on it, that has up to a hundred tiny leads coming off of it, it is probably pretty much locked up and can't be modified. HOWEVER
If you open one and see NOT a big monolithic MCU, but rather two or three DIP MCU's (Dual Inline Package, which is two parallel rows of "legs" coming off it) these are usually pretty good to bend, because the logic between them is compatible voltages, so you can basically rig up every single one of those legs to any other one and get weird scrambled ROM sounds.
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2. Various small toys
With toys you have to think of it this way: all of them are unique, but some basic principles underly all the designs. so when looking for them, u ask urself, how much protection against malfunction
is this toy likely to have? is this a bourgie toy? because what you want are toys that are likely to be prone ot malfunctioning, those are most likely to have cool effects.
A lot of people say newer toys are worse, but thats not necessarily true at all. It is just that a lot of engineers do take a lot more care to make things not malfunction. For instance a lot of newer toys are fucking absolute bullshit because if they are under-voltaged, they will simply turn off completely
, meaning you can no do power starve glitches, and more than likely if the toy is pretentious
enough to be that way, u prob cant do anything else cool to it either.
HOWEVER - a lot of toys still produced have the ability to malfunction etc. If the toy has corporate branding prominent (Frozen, Hannah Montana, etc), then it either is a completely over-engineered
chunk of crap, OR it is a really
cheaply made thing that was made opportunistically to capitalize on branding, and a lot of the time this is actually a good thing for benders, because since the engineers are rushed
to produce something with a brand name on it, they usually skip a lot of practices that protect from malfunction, filter interference, or will just recycle circuits that were alread used and have been in use for a long time.
people often say avoid them, but the "black blob"
IC's are actually often a pretty GOOD sign that the device was rushed into production
and so is a good sign that a lot of malfunction-protection wasn't taken...
Toys to look for
- anything with an obscure brand or no branding, often these are super cheap toys that malfunction a lot even under normal conditions.
- Voice changers and karaoke machines - often times you can just add 1/4" input and output jacks and they are already pretty cool, but a lot of voice changers have clocks that can be modded to run extremely slow or extremely fast, resulting in weird distortion. voice changer IC's and digital echo IC's are a bit scared of voltages higher than 1-3v so be careful not to short them directly... Karaoke machines often times have a dedicated module board for the mic input and echo that is separated from the main board, and if you just read the connectors, you can take that board out, disconnect it from the rest, and power it on itself own, adding inputs and otputs + mods to the echo chip.
- anything that sounds like it has a speech synthesizer (several toys use similar chips for speech synthesis that is in the famous Speak&Spell. a lot of nerds cream their pants when they find a Speak&Spell, but i've bent a dozen or so other toys that use the same speech synth chip, theyre fun but all kind of sound the same. it takes talent to get them to do anything other than just ramble on a bunch of gibberish that gets boring after a while.
- typically, things that don't play a bunch of preset PCM samples. PCM is a bad sign, because usually it means the oscillator that controls the samplerate
is the same one that controls all of the logic required to run the chip, hence change in samplerate also results in the processor not working.
- things with moving parts - often times toys that have moving parts are made kind of cheap, specifically seasonal toys like Halloween or Christmas toys
due to the fact that seasonal merchandise is rushed into production or recycled circuits from other purposes. in general, just think about the design process. if it is something seasonal, it usually has really simple, cheap circuitry and a lot of corners that are cut in prod, for instance if it has moving parts, a lot of the time the sound-related circuitry is simpler and more bend-able because focus had to be taken away from it to focus on the mechanical parts.
- toys that only make one or two simple sounds like a tone or a melody, or sometimes toys which have buttons that each have a short, very low quality sample like sound effects keychains and things like that. generally the lower the quality of the sound, the more likely that it is bend-able.
- One thing to avoid
is toys that just make very simple beeping sounds or melodies that are produced by a piezo instead of an actual speaker
. The worst offender of this is a lot of the "laptop" toys and educational toys. Sometimes you can find a pitch bend, but a lot of them are, once again, monolithic MCU's that are heavily protected from malfunction, and replacing the piezo speaker with a 1/4" output maybe you can get some cool sounds but it is pretty much likely just going to be 1-bit, monophonic square waves.
from speakers to 1/4" output
often time you will want to rip out the speaker and replace it with a 1/4" output. Sometimes this is fine, but some circuits this does not work. this is because of some weird, complicated bullshit called "impedance"
which is basically the amount of resistance between the signal and ground needed to drive whatever thing its attached to. Most circuits are designed with a specific impedance
of the speaker taken into account, so tearing out and replacing the speaker with a 1/4" jack not only leads to you not getting much of a good signal from it, but can also damage the circuit because the circuit is expecting a certain "load" from the speaker
So, you will have to see what the impedance of the speaker is. if it is 8ohms, make sure your output is 8ohms impedance, etc. A quicker way if you dont have proper resistors is using a idfferent ground than the one the speaker normally uses - a lot of the time you can just take the + speaker wire and go to + output jack, and for the negative or ground of the output jack, ust poke around the circuit until you get a signal output that sounds alright. it doesnt matter what, because what your mixer or amp or whatever, cares about, is not necessarily the actual voltage coming from the + or -, but the difference
between the + and -, ie the impedance. a lot of this can basically jst be ignored if you add a volume knob, which is just a pot connecting + to ground cause for the most part the impedance doesnt matter a LOT, as long as there is SOME between the + and -
also, you should probably use a 1uF or 10uF capacitor between the board and your output, and maybe a resistor anyway, because this will remove any DC offset voltage that your mixer or pedals probably wont like.