Jerk Off

Chaotic Jerk module

A true chaos module based on the chaotic jerk equation. The pots really do control the amount of jerk and wiggle in the output waveforms. The input signal can be anything you like although audio rates will have little effect (try tho, it won’t hurt). Feeding it gates or triggers will get the output signals to sync with other modules. The tightness of the syncing is controlled by the input pot. The modules self-oscillate at most pot settings, so can be used without applying any input signals at all.

It is very easy to use this module, try it as an interesting and complex CV source. Good for controlling cut-off on VCFs, VCOs and mixing with envelopes to liven up a patch.

Real chaos is much more interesting than random or pseudo-random as it is unpredictable but operates within a bounded region. It can be compared to a keyboard player. If playing at random, the player just hits any key at any time, maybe interesting for a short while but it gets boring quickly. With chaos, the player may (for example) play an 8 note melody over and over, but each re-iteration is slightly and unpredictably different, perhaps one note is changed, or left out, or the order of two notes is swapped. The variation is subtle but always there.

The module is built to oscillate at approx. 2.5Hz when the pots are set to their midpoints, this frequency can be varied up and down depending upon the pot settings and input signal.

This video shows how the Jerkoff responds to different input signals, it can be seen that the rising edge of the input signal has the greatest effect upon the circuit. You can also see how different the outputs are to each other.

This video shows how the jerk and wiggle of the output signal can be controlled and demos the Jerkoff in use with a VCO and VCF.

At some pot settings, the module simply oscillates and is not chaotic. These settings are known as ‘windows of periodicity’. It is sometimes good to find these settings, then use a CV or gate signal on the input to drive the module in chaotic regions for brief periods.

Controls

Jerk – controls the size of the jerk or kick at the start of each cycle

Wiggle – controls the number of wiggles or ‘bounces’ (think of a bouncing ball) that come after the jerk

In - determines the influence of the input signal over the behaviour of the module

Sockets

In – Does not have to be used, but will allow the module to be controlled in different ways. You can input any signal; CV, gate, trigger or audio. A gate signal will get the jerkoff to sync with the rest of your patch, although how well it syncs can be set with the pots; from nice and tight to something like having a drunken guy in the band not keeping up.

X, Y & Z – these are the three outputs. As seen in the above videos, the signals from these can be very different but are related in frequency at least. Generally X will have sharper edges and Z the smoothest, but this is not always the case. The output signals are bipolar and generally range between +/-5V.