a tiny circuit i designed and built in five copies for dancer Raffaella Galdi. with the help of a small magnetic sensor this circuit makes it possible to start and stop sound coming from a mp3 player. because the five circuit boards, speakers and mp3players are mounted inside pointy hats, the electronics had to be light and draw very little current from the battery.
for the sound volume control i used a vactrol (ldr+led) and the timing and fade in/out logic are encoded in the firmware of a little microcontroller (ATtiny45). to save battery, the tiny45 is put to sleep and is only active when the magnetic reed sensor is triggered. i used the great JeeLib.h for controlling the sleep cycles of the microcontroller.

schematics, firmware and partslist attached below.

Package icon hats.zip29.15 KB


wireless sensor for embroidery.

the sensor is a tilt compensated compass i.e. a 3d accelerometer in combo with a 3d magnetometer. compared to my other wireless boxes, this one runs on 3.0V (two AAA batteries) and not 3.6V. this due to the LSM303DLH sensor's lack of onboard voltage regulators and 1.8V i2c data lines.
the mega168 has an arduino sketch loaded as firmware and is using the internal 8mhz oscillator. so the circuit is pretty minimal.

as part of the project knyppel with ann rosén.

schematics, arduino firmware, partslist, maxpatches, supercollider class attached.

Package icon broderi.zip57.14 KB

soft modem

this summer i build 8 small circuits that can control a bunch of leds (6 channels pwm) from basically any idevice or android phone. the circuit connects to the audio jack of the phone and uses the right channel to send data commands (in the form of a modem signal).

we use rjdj (and pdlib, supercollider, etc) to generate the data signal on the phone in realtime. and it's relatively easy to connect for example the built-in accelerometer in the phone to control some leds, or to run amplitude/pitch tracking on the microphone and let that flash some leds.

the circuits will be used in the rhyme research project as well as in the upcoming e-textile workshop in oslo (oct 2011).

the design is based on SoftModem by arms22. attached below are my schematics, pd fsk abstraction and arduino firmware.

the modem signal is generated using frequency-shift keying and here's how to do that in supercollider...

c= "how are you?";
{var t= 1/1225; var m= Duty.ar(Dseq([t*100]++t.dup(11*c.size)), 0, Dseq([1]++c.ascii.collect{|cc| [0]++(cc.asBinaryString.ascii-48).reverse++[1, 1]}.flat), 2); SinOsc.ar(m*(7350-4900)+4900)!2}.play(fadeTime:0);

this will send the characters "how are you?" at a baudrate of 1225. this is of course not a valid command for the circuit above, just something to demonstrate how it sounds. below is an mp3...

Package icon softModem.zip61.64 KB


things to do with an ipod case... instead of throwing it away, i took some spare parts and built a new synth based on my monijonsyn2. the new synth has a push-button and one can now step through a few different programs. and the 2-way switch set different 'modes'. in this 1.0 version there is only 3 programs and 2 modes.
the programs basically just maps the 3 analog inputs differently, and the modes switches left/right output channels.

it's very cheap and easy to build. 2 aa-batteris provide power, the inputs are 3 touch points, 2 potentiometers, 1 button and a combined on/off/mode switch. all the sound generation (2 pwm pins) and program logic happens inside the 8bit avr mega8 chip and the code is easy to hack (see main.c in the zip below).

todo: add more fun programs to the firmware

Package icon monijonsyn3.zip13.97 KB


my latest controller. i'll premiere it this friday (23july, 2010) at the bring-your-own-laptop event at staalplaat. it inlcludes a light sensor, 2 touch sensors, some big switches and lots of knobs for control. it is also wireless and runs off either a 9v battery or a 9-14v wall adapter. the controller data is picked up by redWirelessMaster and is then read by the computer via a serial port.

firmware, partslist and schematics attached below. a supercollider class for interpreting the data is also included. (101109: minor updates)

photostream from the build process. i took out most of this beautiful old electronics and replaced it with my own circuit board. only kept the front end interface with the nice knobs.

update 130122: supercollider gui class updated and new helpfiles and midi control (via a nanoKontroll).

ipod touch microphone

i bought the klinkenstecker 3,5mm 4pol for €2,40 from segor.de. the capsule microphone i had laying around. sorry no data or idea where i got it. the whole thing is very simple to build and the sound is totally allright. now i can record into the ipod thouch and run apps like rjdj and supercollider with audio input.


for our recent installation at iscm world new music days in växjö (www.musicalfieldsforever.com/searching_voices_conc.html), i built a circuit for controlling 9x5m el-wire (electroluminescence). there are 9 channels in total and 3 inverters that are powering three 5meter cables each. tic201d triacs are used for switching the 110v ac on/off, 9 led+ldr pairs (aka vactrol) generates the control voltage for the triacs and wireless control for the whole thing is obtained with an atmega8 and a pair of nordic transceivers. supercollider is generating the control data.

el-wire_9ch_triacs from redFrik on Vimeo.

Image icon el-wire_9ch_triacs.png39.79 KB
Binary Data el-wire_9ch_triacs.sch95.41 KB


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