thinking up the design for an affordable Janko midi controller

[gguitarwilly]

Hi guys,

I might as well be the first to kickstart this forum again.

Maybe together we can think of a way to make our own custom Janko midi controllers by sharing ideas and knowledge.

What have I found out so far:

- it is possible to lead wires from a great number of key sensors to so called scan-matrices, which are an inbetween thingy between the sensors and a simple computer interpreting the signals coming from the sensors.

- such a computer may be an Arduino, which means the tech stuff needed to build a Janko organ keyboard is very affordable, I guess around 100 dollars.
there are many examples of midified organs to be found, and the stuff needed to make these conversions can be found at https://www.midiboutique.com/

But: I have no idea how many voices could sound simulaneously on such a system, and if there'd be any latency problems. Also, making such a keyboard velocity sensitive is quite another matter.

I asked at midiboutique.com if they could equip a mechanical 6-6 keyboard with velocity-sensitive technology, and to my surprise the answer was no. Well, if even these experts say so, it must be difficult!
So next option: buy a cheap midi controller and use the sensors of that. unfortunately, I found that these 'sensors' are often some kind of grid which cannot be taken apart to accommodate the specific key distance of a janko keyboard. The same with silent piano systems. In these silent systems, all one needs is there already: sensors, computer, midi, and even some onboard sounds.
I've thought about making some kind of keyboard construction similar to my piano conversion, with keys fanning outward from the narrow Janko octave span to a regular piano's dimensions.
But that would mean the midi controller would be far less portable than it could be.

Anyone a suggestion? Maybe there are some techies among you that know how to get a velocity-sensitive signal and multitimbral, non latency midi out of an Arduino?

Willem

[John F]

Hi Willem and others,

I started such a project earlier this year, so I'm really excited to see someone else is also thinking about it. I actually haven't done anything with it for over six months, but now that I've got a few weeks off work, I'll get back into it.

Before starting this project, I had built a couple of Janko adapters. The first one was made of nuts, bolts and 1-inch hex nut caps, which I screwed straight into the keys of an old electronic keyboard!. The second was made of wooden levers and keys, which overlaid onto a standard keyboard.

Then I saw other people 3D-printing janko overlay adapters. So I designed and printed (in PLA) a few octaves of a four-row Janko adapter; each lever has two hex-shaped keys on it, and the entire matrix looks like a long honeycomb. I guess it's similar to other adapters I've seen on Youtube. The levers are all held together by a long rod that runs horizontally through the rear section of adjacent keys, acting also as each lever's pivot. The result is too rickety to be able to play anything with confidence and precision, but I have a few ideas about making it more stable. It was really fun to finally be able to play chords and scales on a real Janko keyboard, after having played them only on my computer touch screen in various music software programs. 

I've not progressed far with the electronics, but I've been learning about Arduino and electronics in general, which is fairly new to me. 

My first goal is to mount my printed keys inside an existing electronic keyboard. This way I don't need to mess about with electronics or build my own key velocity sensors. If it turns out to be satisfactory, then I could probably keep it as a midi controller.

One idea I'd like to pursue is for the keys to be able to trigger assignable notes, so that I can have different tuning layouts (such as Wicki Hayden, although I prefer Janko). To do this, I'll put the outputs from the existing scan matrix of my sacrificial electronic keyboard into an Arduino board, which can then trigger midi notes. Another idea along these lines is to have a pair of Janko rows that is an octave lower than the other rows. This will allow one hand to do open chord voicings that typically need two hands on a standard keyboard (eg, C B D E G, for a typical Cma9 chord). I drew various 6-row layouts in Excel and wrote some VBA code to make it play any cell that was touched or selected. I find this "bass row" idea very appealing, although getting an extra line of sensors under them could be a challenge.

I have looked into the idea of building velocity sensors using force sensitive resistors. I bought some FSR's and tested them with Arduino software just to prove to myself that the idea is viable. There are videos on YT about doing this. Another idea is using proximity sensors. Of course, building the sensors means a lot of extra time and effort and I suspect the end product may not have acceptable consistency amongst all the keys. I'm thinking I don't need to re-invent that wheel just because of having a different keyboard layout.

Let's keep in touch!

John

[gguitarwilly]

Hi John,

Good to hear from you. It sounds like you've really put some effort into solving the problem of how to create your own Janko keyboard.

Could you post a few pics? It's always fun and inspiring to see the fruit of DIY projects.

I've dabbled with Arduino today, with the idea that maybe some day I might understand how I could use it for midi projects. 

But I concluded that to be able to really create one's own projects, it is necessary to dive into c programming, and I'm not sure I'd enjoy that, of if I'd have the patience and talent to arrive at some level that might actually help me with the keyboard project.

I've scaled down my ambition for the moment; a Janko organ would be a nice start, since it would require simple contact switches instead of velocity-sensitive sensors.

The idea of buying a midi keyboard and equipping it with a Janko keyboard is one I've been looking into, but I haven't found a satisfactory way of solving the 'wide to narrow octave span problem'. It would be great to find an existing keyboard which has sensors that can be positioned closer together, but unfortunately these are not the kind of specs you get when looking around the internet.

Let's keep posted on any progress and/or brilliant ideas!

Willem

Op vrijdag 21 december 2018 17:18:01 UTC+1 schreef John F:

[gguitarwilly]

it can be done!

A few accordions were equipped with midi, and even a barometric pressure sensor to emulate bellows pressure.

Here's one of the projects: https://imgur.com/a/U7L83

If only I understood how this worked I'd use this project as a basis for midifying a Janko controller.

Willem

Op woensdag 26 december 2018 14:29:20 UTC+1 schreef gguitarwilly:

[Joseph Austin]

Hi all,

Re Janko Organ:  many years ago I built a Thomas-Heathkit organ kit.  I believe the design it could be adapted to a narrower key-spacing,

perhaps even velocity sensitivity. As I recall, all keys pivoted on a single bar, and the back of each key had a metallic wire finger that traversed the interval between two continuous conductive bars. such that when pressed it would break contact with one bar and make with the other.

If one had narrower keys, they could just be positioned closer together along the pivot bar.

I would assume a circuit could be designed to measure the break-make time and convert that to control touch sensitivity.

It may be that such instruments would be available used--they were  not very expensive even new, so they should be cheap now.

As for programming, I was a professional programmer and have experimented with Arduino and other similar systems.

If y'all need programming assistance I would be glad to help,

BTW, if anyone is familiar with USB programming of LUFA, let me know.

I had been trying to create an Arduino MIDI-mapper for a pair of c-thru Axis 49s,

but could never the the USB Host interface to work.

Joe Austin

--
You received this message because you are subscribed to the Google Groups "Janko-Chromatone" group.
To unsubscribe from this group and stop receiving emails from it, send an email to janko-chromato...@googlegroups.com.
Visit this group at https://groups.google.com/group/janko-chromatone.
To view this discussion on the web visit https://groups.google.com/d/msgid/janko-chromatone/5b0dc8bc-1396-40b7-9af9-d6090e937040%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[John F]

Willem,

There are midi controllers with narrower keys on the market; e.g., the Korg Microkey has an octave span of 140mm. I don't think you'd want to go much less than that. As you'd know, an octave of full-sized keys is about 165mm.

I would also like to have a smaller octave span. For the time being, though, I've already printed my keys for my full-sized Casio keyboard, so I'll stay with my current specs. 

The idea of 3D-printing my keys was sparked by seeing Ian van Loyden's 3D printable keys. He seems to be an engineer and has designed very nice looking keys and sells them in octaves I believe.

You can see one of my humble 3D-printed adaptor levers in the attached photo. They're quite chunky in this first design, as I wanted to make them adjustable to tweak the key height, shape and size. Each lever has threaded holes into which is screwed a riser (threaded nylon rod), atop of which is screwed the hexagonal key. I'm using threaded rod so that I can adjust the heights of the keys. The hexagonal key consists of two parts: a base, which screws onto the riser, and the actual key top, which clicks onto the base. I did it this way so that I could tweak the shape of the key top. Once I've settled on optimum heights and shape, then I need to think about a different design for the lever and riser, so that it has less flex and sideways movement. All ideas and comments are welcome!

Converting my keyboard overlay adapter to a set of individual sensor-triggering keys will mean that I need to redesign my keys to physically mount over the existing sensors of my Casio. I also need to give thought to the spring mechanism to make the keys rise up. Considering this, perhaps I'll first try using the existing keys of my Casio as the levers of my adaptor (as the Casio keys are already designed to fit the sensors perfectly and already have a spring action).  I could attach the risers of my keys directly onto the Casio keys by gluing nylon threaded nuts onto the keys. I expect the additional weight of the Janko keys on the Casio keys will affect the spring action, but I'll address that problem when it arises.

[John F]

Hi Joe,

I'm definitely a hacker when it comes to programming, so I might take up your offer of assistance when I get to that stage of my project.

:)

John 

[Omar Soriano]

hey all.  Don't have much to contribute to the discussion. Just want to say that its cool that people are still talking about this. 

[gguitarwilly]

Hi John,

I'm really excited that people like you are still trying to create their own Janko controllers! It should be possible to come to one or more working designs if we share ideas and knowledge.

I peeked at a web page 'diykeyboard' that was posted on the Facebook Janko forum, but not much seemed to be happening there. Maybe that would be the ideal space to share ideas?

You wrote you're good at programming; could I ask you to have a look at the attached text file? 

It is the code for an Arduino project that uses three qwerty keyboards for generating midi output. https://www.youtube.com/watch?v=NtWRIHYDzWQ&t=64s

For now I would be happy to get any kind of midi signal coming from a single qwerty keyboard linked to an Arduino, so the code needs to be modified accordingly. But I'm also intrigued by Joe's idea to use the time elapsing between breaking a contact and making a new contact to create a midi signal that conveys velocity information. So if you have an idea for a code that could make that work for two contacts on an Arduino breadboard, I'd find that an interesting start.

Willem

Op woensdag 26 december 2018 17:21:12 UTC+1 schreef John F:

[gguitarwilly]

Hi John,

I realise that modifying the code file alone will have no effect: the libraries will have to be modified (they can be found in the description of the youtube tutorial) as well.

Willem

Op donderdag 3 januari 2019 12:32:03 UTC+1 schreef gguitarwilly:

[gguitarwilly]

Hi Omar,

are you still playing Chromatone?

Willem

Op donderdag 27 december 2018 22:08:11 UTC+1 schreef Omar Soriano:

[gguitarwilly]

https://www.youtube.com/watch?v=mpeTHLr1vlc

Op zondag 16 december 2018 11:38:54 UTC+1 schreef gguitarwilly: