This is a review of all the versions of miniMO to date, from newest to oldest.
2017-18: midiMO (current)
midiMO is the affectionate name I give to a miniMO loaded with a MIDI-related program (like the sequencer), using an adapter that allows it to send MIDI messages to external gear. I released it in (very) late 2017, and so far it is the latest addition to the ecosystem .
- 3D printed-based model (current)
I was happy with the 3D model, but I felt the breadboarded version still had a place in this world, so I took it as a challenge to update it. I redesigned it with the same constraints as the PCB model, fit all the components straight on the board and figured out how to connect everything with no soldering.
I’m called this model the Noisette, and shifted from naming it as a breadboarded model to 3D printed model, as was now its more salient feature. I also wrote an extensive guide on how to build and program it, which takes me to the next point,
- Open everything
I started this project as open source; gradually, I’ve moved towards open hardware, publishing files for all parts, accessories, and schematics.
2016: PCB-based model (current)
Come Christmas 2015 I built and took a latte to Toronto, where I demoed it briefly to the nice folks at the Moog Audio store. Everything went well, people liked the design and I got great feedback on the sound and feel. I realized, though, that if I wanted to build more than a handful units and demo them reliably I needed a model that I could build quickly and send by mail not fearing it could break during transit. I set to work on a PCB-based design, and while at it I also decided to see how much I could bring costs down.
The redesign eschews third-party circuits, features a jumper to select from external or battery power, and has identical outputs (previous models filtered them differently). I also designed a number of accessories, from connectors to external cases (see here).
I worked on this unit for most part of the year, and made a minor revision to the circuit in September, based on external feedback and my own experiences with it.
I also designed many 3D- printed parts for this model, including legs, cases and connectors.
Finally, I set this website up and started a Github repository to share all the relevant materials.
2014-15: Breadboard-based models
In late 2013, a series of conversations with my friend Mateo spurred his development of what now are the Hypercubes. I offered to help, but my electronics skills were still very low and all his modules were analog, so I dusted the ATtiny and started to work on a digital module. I thought it would be interesting to show it in addition but also in contrast to the analog modules, both in terms of inner workings and versatility.
Initially I was trying to follow the hypercube template, so I placed a potentiometer and push button together in an encasing that would fit at the top of the cube.
I couldn’t find mini boards with side rails, so I 3D printed custom boards and cannibalized the metal channels from boards I had around.
Eventually Mateo and I parted creative ways and I decided to continue working on the digital module. For a while I gave away with the external enclosure and placed the potentiometer+button combo on an arch over the board.
I liked this design, but I wanted it to become portable and easier to connect to other gear. At the time I was running the ATtiny at 16Mhz, so I added a 9-volt battery and a 7805 regulator, eventually replaced by a more efficient model from Pololu. I also added a power switch and mini jacks, and moved the LED, a Neopixel from Adafruit, up; finally, I designed a new enclosure. A friend suggested I could use minimo for the name, so I incorporated it to the design.
The enclosure comes out easily, and the top components don’t connect directly to the board, so it takes maybe half a minute to disconnect and reconnect them all.
I took this version to a workshop in November-December 2014 in Madrid by Bleeps&Chips and demoed it to friends. The push button proved unreliable, so later on I moved it from its position under the potentiometer to the spot occupied by the power switch. I replaced the potentiometer with a model including an embedded switch to make up for the lost space, and designed a new battery compartment to hold two cr2032 batteries, with a smaller footprint that the 9-volt. I printed the enclosure in the then novelty wood filament from FormFutura, and thought it fitting to call this version the Caffelatte.
I printed all the parts for a couple new lattes, then set on to work in other projects for most of 2015.
2009: Early sketches of what was then the LMS, or Little Modular Synth.
The modules would connect via magnets; distant connections would use cables with magnets at the ends.
I knew almost no electronics at the time, so these sketches remained at the back of my mind until in 2012 a friend suggested I could use an Atmel ATtiny and a DAC to generate tones.