Simple DIY Eurorack modules

First some pictures.

What you see is what you get:

Green: Slew limiter / portamento / glide. It limits the speed of change. It has a switch to limit up/down/both.

White: Passive OR-wired sockets. It is likely exactly the same as the Doepfer A-186. It combines up to 7 gate, trigger or analog signals by or-wiring. If all the inputs are low, the output is low. If one of them is high, the output is high. You can use this module to combine trigger signals. See the Doepfer DIY on how you can make this module.

White: Dual passive AND-wired sockets. A double 2-input, 1-output passive AND gate. If both of the inputs are high, the output is high. See Doepfer DIY on how to make this module.

Blue: Passive multiple, like the Doepfer A-180. Use this double 4-fold multiples to split some signal and route them to multiple destinations. For sensitive applications like a VCO a buffered multiple is recommended.

The front faces are 3d printed, models can be found at my Eurorack module thing at Thingiverse.



Intro.

So I recently got a VCO, VCF, LFOs, VCA from Doepfer. A visit to London Modular brought me a DIY kit for RYO VC Sequencer from LJunggren Audio (awesome kit btw, it took me 6 hours to solder). Here is where I start. With this set, you can already make some awesome patches. But if you know me a little bit, I always want more :-) The modules aren't cheap, so here we go.

Firstly, building your own module is a lot more satisfying than just buying one. You learn a lot too. There must be some modules that are easy to make on your own, especially when you can 3d print the front faces yourself. I'm not very good in electronics, but I built many things before: see this site and http://amplivibe.com.

Preparation.

• I found this awesome Doepfer DIY website. Very useful explanations and some ideas.
• A lot of schematics use op-amps. What are they and how do they work? Read about op-amps and watch Op-amp video. Now you understand schematics better.
• Good general tips and some interesting projects: Dintree.
• Yusynth. An awesome guy that apparently makes a lot of modules and post them online. He also worked on the Arturia Minibrute, which I own. But the projects he does is just a bridge too far (for now).

Experimentation.

Play with op-amps (TL082), inverting amplifier, non inverting amplifier, set the offset of some signals, attenuate signals. I do this using a breadboard. Get a lot of 1k resistors (as well as 10k, 100 Ohm). Try out some values.

Build.

After some fiddling with wires, breadboards, ic's, resistors, caps, etc. it would be nice to finally have something fixed in the modular case. Only when a module sits in the case, it feels like it is finished. In a lot of cases there is some pcb involved, which must be mounted somehow to the front plate. Using my MendelMax 1.5 3D printer I've made some blind plates first. They are not very stiff, so for modules I added some stuff to make it stiff and I added mounting holes for some particular pcbs. For more info, mail me!