Music Thing Modular Turing Machine Mk 2

April 6, 2016

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

Full kits will soon be available from Thonk 

Design files are in the Music Thing Github.     (Full documentation and BOM are on the way)


  1. Eric Cheslak says:

    Any idea when the kits will be available?

  2. Laughing says:

    The link there for the design files just links to Thonk again, is that a mistake?

  3. Dominic says:

    Hey Tom

    I recently purchased the Voltages pcbs and panel from thonk and am trying to locate a BOM for this module.

    Can I use the BOM from the old version for the new version?

    Many Thanks!

  4. TURING Mk.2 says:

    Hello Tom;
    we love the module but there is a problem with the offset. Turned right the machine does not freeze totally but still inserts new events in the register — not very ofter but very 10 seconds — so:
    IS THERE AN OFFSET for the CV that can be adjusted or is the unit broken?
    1 question about VOLTS:
    With end of the triggering gate Volts falls back 0 V — is that normal? So: Do I really need an additional S/H and a multiples to get rid of that issue???



  5. TURING Mk.2 says:

    Hi Tom,
    Will try calibration in the next days.
    Volts were and are connected correctly — so that is not the problem. Still bouncing down to earth tones 🙁
    Any other suggestions?

    • Tom Whitwell says:

      Yes, with nothing lit, it should be outputting 0v – that’s the normal behaviour. If 0v is too deep, tune your oscillator so that 0v is a more useful tone, and a wiggle accordingly!

  6. Curt says:

    Hi Tom,
    any news for me — thanks?

  7. Curt says:

    Hi Tom,
    beg you a pardon: the exact level that PULSES is to falling back to was not my concern. I was asking you initially: when the gate pule triggering PULSES has ended, does it

    A: hold the level until a new pulse forwards the signal to the next of the five adjustable stages of PULSES or

    B: does it fall back to ZERO in between the stages. So in consequqnce of B a S/H module would be indispensable for an operation that could make sense in a melodical envisonment 🙂

    Any questions: Feel free to ask!



    • Tom Whitwell says:

      Pulses = falls to zero between steps – the width of the pulse is the same as the width of the incoming clock pulse
      Volts / Voltages = steady voltages – the voltage changes with the rise of the incoming clock pulse, and stays there until the next incoming clock pulse

  8. Jonas Fehr says:

    Is the turing machine also capable of taking +-15V?
    Great work so far, now I am looking forward to run it.

  9. kelz says:

    I am finding it difficult to find the Turing Machine mk2 module for sale anywhere ?

  10. Marius says:

    already an idea when there will be new kits at thonk?
    The link in the description is broken.

  11. ello says:

    heya, i have a question regarding the noise output. what is supposed to be there, as i have no idea what comes out of this output. to me it seems there is nothing going out.

    any ideas?

  12. ello says:

    oh, thats not happening on mine. any advise where to look at? it is self built… random cv works

  13. ello says:

    Ah 🙂 its working now. seems i turned the trim pot a bit too much counterclockwise. and the cv generation seems to work better now, too.

  14. Rafi says:

    Forgive previous message spelling is way off. On start up all LEDs light up red . When I send a square LFO to the Clock input clock, click input light reflect speed of LFO, but then lights above shut off doesn’t seem like normal function

  15. Rafi says:

    Yes, I’ve watched Divkids’s vid several times, that’s why I know there seems to be an issue. When I send a square LFO to the clock in the top LEDs go away and no random LED sequences appear above. When I click up to write a sequence it will register LED movement but will not loop around and just disappear.

  16. George says:

    Hi, I’m not getting any noise from my MK2 Turing Machine. I’ve changed the 2n3904 and the TL074 still no noise and nothing when probed with a scope, any ideas? Cheers, George

  17. Robert says:

    I got mine yesterday from Thonk. Beautiful packaging. Impressed with the attention to detail and everything included speaks quality. I got stickers and a button. All very pro. After about 3 hours of soldering I had it ready. Lucky to get it working on the first try. Calibration took a minute. Results are great; totally thrilled to up my game with this module. I’m just now reading the manual. Wanted to say thanks.

  18. Martyn says:

    I have recently bought a Turning Machine and 1x volts expander. I would like to know how many additional Volts expanders I can chain to use for different modules (eg with my Blue Lantern Quad Quantizer)?

    • Tom Whitwell says:

      Hi, you should certainly be able to attach 4 – probably many more; with no LEDs, these don’t draw much current at all.

  19. Phil t says:

    Not sure if this has been brought to your attention. The mk2 machine, when in left lock if you erase all bits it will write 8 bits with it locked, is there a fix for this?

    • Tom Whitwell says:

      This is normal behaviour.
      If the lock is fully left, it will reverse 100% of bits; so every 0 becomes 1 at the end of the cycle, every 1 becomes 0. If the lock is fully right, it will reverse 0% of bits bits, so every 0 stays as 0. With the lock knob in the middle, it will reverse 50% of bits, creating a random pattern.

  20. John McEwen says:

    Hi Tom,
    I love the Turing Machine and purchased 2 expanders. However, my Turing Machine loses power after about 10 minutes. Any idea why this might be happening? It seems like it might be a heat problem because it’s starts out losing power at about 10 minutes and then I have to completely unplug it to get it working again. After that it progressively loses power in shorter durations. I tried re-soldering the power adapter but I’m not sure if you have ever run into this before and found the reason why? Can you help?

  21. sandro says:


    My one just runs on the first 4 steps… the other 4 doesn’t work.
    how can i fix this problem?

    • Tom Whitwell says:

      Hi, sorry to hear that. It could be an issue with the 4015 shift registers – check the chips and if possible replace them, or swap the two chips around and see if you get a different response.

  22. Ciprian says:

    Hey. Just finished assembling it. Any chance anyone knows what could I have been missing if the 8 bit is not working at all. Any help direction to forum greatly appreciated.

  23. Hi Tom, are there build documents for pulses mkii and new volts expander? I just bought them for my first ever builds. Thonk has link to build docs but they just at show pics of PCB. Thonk is not getting back to me. Thanks!

  24. Ian Myers says:

    Hi Tom,
    Just finished a successful build of TM mk2 and plan to add a volts (maybe two) pulses and vactrol mix expanders. I now have a volts to build and am now thinking of the interlinking cables needed to run the expanders off of the single TM. Is there a sketch or diagram showing the necessary interlink cables needed?

  25. max m says:

    Hello Tom,
    built the turing machine about a year ago, but with a normal instead of the momentary switch. Everything worked as it should. Today I replaced the switch for a momentary one and now it doesnt put out any cv anymore, also the noise out is completely silent. Other than that it seems to work if I look just at the leds. I tried recalibrating with the trimmer fully clockwise but no effect. Maybe I fried some component?

  26. Ab says:

    Can this be clocked at audio rate?