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Category Archives: circuit bending




here is a little jam to test the possibilities of my recently finished step sequencer…this little gadget is so much fun, and opens up my head of possibilities…i have to write a proper post with circuit and instructions on how to build it i will just say for now that is made with a single 4017 that can trigger 4 different channels on each of the 10 possible steps.

here comes the sound…

…on the video I’m playing the sequencer and the SP-404 sampler trying to match tempo…and the sp404 is also filtering the sequenced sounds at times…and the drum pattern at others….the step sequencer is triggering the sounds of a toy circuit which i modified adding also pitch and distortion controls….plus the jacks connect the 4 channels of the sequencer to the desired sound bank on the toy…


this are some images of the process of building the 4017 step sequencer and a little circuit diagram…the construction was not difficult but  tedious….

9volts 2009


let’s start with a video:

(thanx again for the recording to LucySombra):

I made this project a year ago, using the mechanics of  (his master’s voice) old Victrola, found on the streets of Barcelona, by jan (thanx again man) and brought to me to salvage it’s still usable parts, the poor thing had ended it’s life as a record player on the trash, needle and arm missing, cone sound missing, etc… BUT the only one thing remaining, and the most important to me was the cranked  spring engine, with it’s old school system to keep speed regular…

seqenciador mechanico

The result is a very interesting cranked beat sequencer,  it has four radial channels, with 24 steps each, each step is one hole on the plate, where small plastic pieces (from “mastermind” game, also trashed out from bcn) can be placed to trigger a sound. Each channel is aligned with a momentary switch which when contacting one of the plastic pieces triggers the sound assigned to that channel.



There is two different circuits that can be used interactively with each other. On one side a simple drum toy with four drum sounds, some basic bending like pitch control (for all the sounds at the same time), and body contacts for distortion mode 1 and 2, and in the other side a simple pitch controllable oscillator circuit for each channel, (made with just one  4093).


it’s is an open sequencer because any source can be triggered by plugging it’s push button trigger poles  to one of the rca connectors on the back, that is how the drum toy circuit encased in the box is triggered. that also means than the sounds triggered by each channel can be easily swapped on the fly by others by just plugging the desired source on the desired channel.



on the other hand both circuit’s have independent volume control to be able to tune the mix levels, some times oscillators can be loud… the yellow buttons also trigger each channel for longer manually operated notes.



click to enlarge

this circuit comes from a teddy bear, which had 8 a spanish voice sounds. and i modified the circuit with usual basic bends like pitch resistor replacement for a pot and body contacts….after a little more investigation, found some interesting glitching distortions, adding capacitors of different values… also added the looped sound trigger mode…

everything was then recased into a beautiful old electronic vintage chess game from my grandfather…

what does what on the chaos

and of course i had to add the reglamentary audio out, because the sound quality of this circuit improves dramatically when connected to an external amplifyer…

back view of the chaos champion

and finally here is a video of the champ of chaosssssssfrgegrfg…..

another bend from 9volts

ok this is an old info, but an update at least…

this is a link to the info about the expo we did last sumer:

and the interview on the newspaper ELMUNDO catalunya ; the text is in catalan, so sorry for the non catalan speakers and here a picture taken for the article…

hardware hacking

ok back again…

casio pt-1

this is the 2nd CASIO keyboard I circuit bent…as usual the controls are placed on a extension unit through a serial cable because of the small space left inside the keyboard case…the box was a speaker from Virreina church in Gracia…(found beside it)

again no diagrams yet until I am back on my workshop in Barcelona… anyway if i’m not wrong, there was not many interesting glitch points on the board but the ones coming from the big chip in the left side… as soon as i get my hands on my notes i will update this post with a couple diagrams…

what does what

like in the other keyboard (PT-87) i tried to find alterations for the on board rhythms section, kind of low-pass filter and high pass filter, some distortions, and two interesting bass-lines heartbeat like that can be controlled with pots… On the other side, the pitch resistor was substituted by a long fader with a higher value than the original on board little pot which takes the rhythm tempo and pitch to an extremely slow speed, turning hit hats and drums in to beautiful noisy crash sounds, three body contact points were also added to achieve a more natural hands on way of playing, some of this points were duplicated to give more resolution to the effect…

body contacts

and finally a reset button (disconecting batteries) for when things go really wrong, (if it can be considered wrong when the little beast takes control of it’s own grunts…

and here a video:

another hack by 9volts

update: i found some pics of the circuit board with some bend points soldered ; don’t remember right now what does what as i said i will update later here is the pic:

some interesting points on PT-1 circuit board