Sneak Preview – Preliminary Spec

The Bonkulator is a Eurorack module that fits into a 3U x 14HP slot. It features 8 programmable outputs and 6 programmable inputs. The front-panel user controls consist of a 128×64 pixel 2-color OLED display, a rotary encoder for adjusting parameters and a button for each trigger and output.

Pressing and holding the trigger buttons toggle the trigger enable/disable. Pressing the output buttons brings up the configuration menu for each output.

In addition to the front panel controls, the Bonkulator provides WiFi and Terminal interfaces. The WiFi interface is a REST API and the Terminal interface is ANSI X3.64 via the Arduino micro-USB connector. These interfaces greatly extend the usefulness and capabilities of the Bonkulator. Scripting, patch management, dedicated GUIs and even Internet-connected IoT apps are now possible. And using a remote interface means that you no longer have to adjust tiny dials amid a forest of patch cords. This benefit cannot be fully appreciated until it is experienced directly.

Note: this is a preliminary spec and is subject to change.

8 Outputs

  • In general, the output value follows a selected shape.
  • Shapes can be from the factory list or user defined.
  • Factory shapes include ramp-up, ramp-down, sine, haystack and others.
  • Shapes can contain from 1 to 128 steps.
  • Outputs can be programmed to be one of the following.
    • Envelope
      • +/- 5V analog signal
      • Output value follows the selected shape
    • Pulses
      • Pulse width follows shape
      • #-of-pulses can be set from 1 to 999
      • High and low values can be set from +/-5V
    • Toggle
      • Toggles at end of period of selected output
      • High and low values can be set from +/-5V
  • Outputs can be programmed to be triggered or clocked by any of the trigger inputs.
  • Outputs can be triggered by multiple triggers.
  • Initial delay after trigger is programmable from 0 to 99999 ms.
  • Blanking period after trigger is programmable from 0 to 99999 ms.
  • Outputs can be scaled by UI setting or by CV input.
  • Outputs can be offset by UI setting or by CV input.
  • Output period can be set via UI or by CV input.
  • Output repetitions can be set from 1 to 65,535.
  • Output quantization can be enabled or disabled.
  • Output can be randomized from 0-99%.
  • Outputs have LED level indicators

4 Trigger/Clock Inputs

  • Triggers activate output functions.
  • When Output is set to Ext Clk mode, trigger inputs increment the shape step.
  • The trigger inputs respond to a positive-going signal or a button press.
  • Each trigger can be independently enabled or disabled.
  • An LED indicates when any attached output is active. This LED will also flash in a distinctive pattern to indicate when the trigger is disabled.

2 CV Inputs

  • +/-5V input range.
  • CV inputs can control many of the output parameters.
  • LED level indicators.


  • Envelope generator
  • Rhythm generator
  • Pulse stretcher/multiplier
  • Sample and Hold
  • LFO
  • Sequencer
  • Quantizer
  • Randomizer
  • and moreā€¦

2 Replies to “Bonkulator”

    1. I plan to do this in stages. At first it will be totally DIY with all the files needed to build on Github. Next would be to offer board/panel on a site like Tindie. Possibly a full kit option. And maybe someday we can offer fully assembled and tested units.
      Currently JLCPCB is making 2 boards with all components on the bottom side (except 3 SMT ICs) installed. I bought the missing ICs from Digi-key. The total looks to be around $225 US for the two.
      It will be a while before the Bonkulator is available. I haven’t started on the code yet. But, you should check out the Spankulator. It is available now and has many of the same features. Plus it has a fully-developed Web interface.
      Thanks for checking in!

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