Since it was launched in June 2012, the Turing Machine has become one of the most popular Eurorack DIY projects. It is a random looping sequencer that spits out basslines and melodies. It generates strings of random voltages that can be locked into looping sequences.
These sequences can be allowed to slip, changing gradually over time. This module was inspired by the long history of shift register pseudorandom synth circuits, including the Triadex Muse, Buchla 266 Source of Uncertainly and Grant Richter’s Noisering.
The 2016 revised Turing Machine has many improvements:
- Rotary loop length switch
- Pulse out
- Easier to build: a larger PCB in the same width, clock and noise circuits are more robust
- Compatible with existing expanders
Multiple mini expanders can be daisychained from one Turing sequencer to give melodically different outputs that are all related to (and change with) the main Turing sequence.
There are 4 different expanders available:
Pulses MK1 Kit: a random, looping clock divider, with seven pulse outputs, controlled by the main module. The clock length follows the clock input, so can be controlled if you have a square wave LFO with pulse width modulation.
Voltages: an eight stage random looping step sequencer with illuminated faders, controlled by the main module. Unusually, any number of stages can be active at once, creating unpredictable results. It has two outputs, one normal – with a scale control that works in the same was as the similar control on the main module – and one inverted. The inverted output has a ‘shift’ control which raises (offsets) the voltage by up to 9 volts. This means you can drive positive-only modules (i.e. quantizers) with the inverted output.
New Pulses (MK2): This is a slightly updated version of the Turing Machine Pulse Expander, with more outputs. It uses SMD components, but is still a very easy build.
VOLTS (New Volts): This is a simple, low-parts count, low-current expander for the Turing Machine Random Sequencer in 4HP. It acts like a variable 5-bit digital-to-analog converter, taking 5 bits from the Turing Machine GATES expansion port, running them through five potentiometers and giving one summed voltage output.