Chaotica Full Kit

The IF120 is a multi-featured, autonomous, third-order chaos circuit.

This is for a full kit in the Eurorack format

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This module is a multi-featured, autonomous, third-order chaos-generating circuit. Its features include (1) a third order response (ie, three outputs) with a total of four nonlinear elements in the circuit path, (2) switch selectable nonlinear elements, (3) voltage control of rate, loop damping, gain and offset, and (4) a reset/inhibit input which allows the system to be set to zero voltage at all three integration stages. Please see for oscilloscope photos of typical chaotic patterns (attractors) along with demo sound clips and a video.

The controls on a chaos generator are different from those on other synth modules. The best way to learn their functions is to experiment with them. Here are brief descriptions of the functions.

  • RATE: This is the speed at which the signal traces out its patterns. It is similar to the frequency control of a VCO or VCF. It has an initial setting (to the right) and a standard modulation input (input jack and depth control, to the left). Rates range from slow, creeping LFO-like sweeps, well up into audio frequencies.
  • DAMPING: Damping is a linear negative feedback around one stage within the circuit. Too little damping will cause the signals to run away to the rails. Large amounts of damping can cause the signal to die out altogether. Damping is similar to resonance in a VCF, with less damping analagous to more resonance. As with the rate control, there is a control for the initial amount along with a standard CV input.
  • OFFSET: It turns out that a DC offset voltage within the main circuit loop is an important parameter in this circuits. Its main effect is to change the overall signal amplitudes, ie the size of the chaotic attractor. Again, this parameter is under voltage control in Chaotica.
  • GAIN: This is the overall (global) gain in the main circuit loop. It's just a little internal VCA! The amount of gain affects the overall size of the attractor, as well as the the amount of damping. The damping and gain controls work together in determining the chaotic pattern generated. Also voltage controllable.
  • NL DRIVE: Nonlinear drive amount. Chaotic behavior in an electronic circuit comes from internal feedback loops containing nonlinear circuit elements. The NL Drive control varies the amount of feedback of one of these loops. This is one of the controls determining the strength of the chaotic pattern.
  • TAME/WILD: This switch sets the strength of the second nonlinear feedback loop of the circuit. Wild and Tame refer to the wiggliness of the signals.
  • 1/2 EYES: "Eyes" refers to the overall shape of the attractor pattern. This can have a single center (1 eye) or two separate ones (2 eyes). Please have a look at the patterns as shown on my site.
  • RESET-INHIBIT: This input jack is intended to receive rectangular pulses. When the pulses are high, the oscillations are halted and the system returns to a state with all voltages at zero. A narrow pulse will simply reset the system, whereas a wide pulse or gate will hold the system off. Putting in narrow pulses and varying their frequency will illustrate the evolution of the attractor. Can also be used to produce periodic signals with many interesting vocal characteristics. X, Y, Z: The three output signal. These signals are highly correlated, and are typically used to vary the CV inputs of various modules in a patch.

Specs & Downloads

Specs & Downloads

100 Elby
HP 20
Depth 94mm
+12V 4mA
-12V 3mA
+5V No
Additional Resources Users Guide Build Guide Component Overlay Bill of Materials


Customer Reviews (1)

Great module. Well organized parts. One bad switchReview by O.Z. Hall
I've completed the Chaotica module. I thought the price was high for the full kit, until I received it. Lotza pcbs & cables included. The parts were well organized. I had real difficulty figuring out how the side/by/side switches and jacks mounted to the circuit board. I could not find a picture of the rear of the module anywhere on the internet.

Once I got the module assembled, I found that one of the switches was bad. The connection on the down position was intermittent. I replaced the switch and it works find.

The jacks are a little loose, but seem to work most of the time. The quality of the other components was good.

I would recommend this kit to a friend. (Posted on 12/12/2017)

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