Eurorack module testing tool (DIY)


I had to face two problems during the development of the modules:

  • How to power and test them during development? A bench-top supply and signal generators? Too big and overkill. My rack loaded with precious stuff? No way I would let a scope probe shorting two pins impact them!
  • What kind of setup to use for factory testing? A Doepfer mini case loaded with LFO/signal generators? Too expensive, and hard to operate.

I decided to find a DIY solution, and designed the following box.

It serves the following purposes:

  • +/-12V and +5V power supply with euro connector.
  • 4 signal generation channels dedicated to clocks (tempo, resolution, pulse width); gates (period, pulse duration); CV (several waveforms, sequences stepping through 1V/Oct octaves or scales); and audio (fixed note/frequency tone generator with various waveshapes).
  • 2 signal acquisition channels, one is audio with frequency and note interval measurement (for V/Oct calibration) and the other is digital for clock testing/calibration (frequency/tempo measurement; and pulse width).

Maybe this might be useful to those of you building DIY modules and wanting a quick test/debugging setup less cumbersome than signal generators or your modular setup?

It won’t go farther than Board+programmed MCU+Mouser BOM with very minimal assistance provided (no building instructions etc). This might be useful to hardcore DIYers only anyway!


Very interesting tool Olivier, leave it to you to innovate this way.


a diy diy tool - very self-referential. :wink:


oh nice.


Very cool I’ve been wanting something like this for ages!


yep where do I sign up …


I think this will be helpful for me (and probably many others) make friends for my surely inevitable MI modules in my now inevitable eurorack case


Oh yes! Will free up a bunch of eurorack modules currently being pressed into service as signal generators, and I’ve been looking for a better frequency measurement solution than my multimeter for a while. Want!

PS What sort of MCU does it use?


Good old ATmega… It’s a very simple Shruthi-like through-hole board.




Its the 3nd most usefull thing right after sufficient gravity/air/light and a Scope when developing something Eurorack/DIY




Hmm, this will go into the cart when available.


Will there be a FrankDanielsPlexiCase™?


Available on request.




I think I’ll get one of these when it’s available, I used to be powering my breadboard modules using a one meter long ribbon cable plugged to my euro case, and was always worried I could fry my real modules, then I started to use a separate Euro PSU, but it’s cumbersome… This will come handy!


Could this be modded to other modular synth formats, i.e. +/- 15V and MOTM?


+/- 15V -> change the regulators. MOTM: this is the format of the connector, right? Or any other change?


yeah i’m up for this one too¬¬!

really great idea.