Sunday, 8 September 2019

Turing Machine

The latest kit I built is the Music Thing Modular Turing Machine mkII

Turing Machine chilling on desk
Even if the boards are quite crowded, this is an easy build, thanks to the excellent documentation that comes with it.  The online build manual from Thonk is very well organized (smallest parts to tallest) and massively illustrated.  The fact that both value and component references are printed on the board is a real bonus.

Resistors first
Nothing special to tell, apart from the fact I soldered a 51k resistor instead of a 5.1k.  I simply misread and didn't double check.  Nothing serious : desoldering the wrong one, soldering the good one.

I used the documented trick to put some masking tape to align the diodes to the facade.  My diodes were well aligned but this left some greasy mark on the beautiful  facade.
Make sure your masking tape is not too old and will not leave marks by testing on the back side !

Finished boards

What is a Turing Machine ?

Bob calibrates the module
It is a pseudo random looping sequencer made from logic chips.  It is based around a shift register circuit.
You cannot program it or save sequences.  It produces clocked randomly changing control voltages.
The big knob controls how much randomness you put into it.  At noon, you're supposed to have a fully random sequence.  The more you go left or right, the more the loop is locked and stable, according to the length control.

Being fully made from logic chips with no software, the module can be clocked at audio rates to creates random wavetables as well.

Ready to assemble !

A word about the name by the designer, Tom Whitwell : "The Turing Machine is not a real Turing Machine the way Alan Turing explained it. The name is vaguely relevant because the module uses a loop of data being changed, but computer scientists find it very annoying. "

In the rack
Finally, here is a sonic example of a piece composed of 4 random tracks where the pulse output of the Turing Machine triggers an envelope and the output is passed through a quantizer to produce exact notes.  I added some pads and drums from software synths and voilà :


  1. Just found your site from Muff Wiggler. Very helpful.
    What is the "documented trick to put some masking tape to align the diodes to the facade"? Google was no help and I haven't purchased the Turing Machine kit yet. (But I have struggled to perfectly align my diodes!)

    1. Hello. thanks for the feedback.
      The trick is documented in the Thonk building guide : "If you want to fit the flat head LEDs so they fit flush to the panel then apply masking tape over the 10 LED holes in the front panel."

  2. Ah, thanks. That makes sense. Enjoyed listening to your test track above.