robot porn

Nintendo DS = wireless MIDI controller

Tob has just told me about DSMidiWifi — a program for Nintendo DS handheld gaming consoles that sends out MIDI data to a host application on a computer. Play any MIDI instrument, virtual or real, by tapping on the DS’s touchscreen, KaossPad-style. (Actually, you can control anything controllable via MIDI, which is about everything electrical in existance, given the right interface.) Chiptune fans also can have the DS receive MIDI data in realtime and use it as an instrument.

Now I really consider having a DS on my x-mas wishlist…

voc, bs, dr, shirt

wmmna brings us the news of a wearable “air guitar” controller disguised as a regular T-shirt:

‘Freedom of movement is a great feature of these textile-based interfaces,’ [Dr Richard Helmer] says. ‘Our air guitar consists of a wearable sensor interface embedded in a conventional ’shirt’, with custom software to map gestures with audio samples. It’s an easy-to-use, virtual instrument that allows real-time music making, even by players without significant musical or computing skills. It allows you to jump around and the sound generated is just like an original mp3.’

Heh. He said “original mp3″. But besides, Régine also mentions the Bangarama developed by Students at Aachen’s RWTH university two years ago: A helmet to convert headbanging into guitar sounds using an acceleration sensor. That could be a cool add-on for my MIDI key-/guitar (still unfinished).

C64 Keytar

While the MIDI keytar still looms at a considerable distance from being finished, here’s something else for the impatient audience:

Commodore itself released a cartridge for their C64 home computer in 1983 called “Music Machine”. While most of the C64’s software was loaded from cassette tapes or floppy disks, there were some games and applications available as cartridges that loaded instantly into memory on power-up, bypassing the usual BASIC screen. This makes cartridges perfect for immediate use: no loading times and no additional hardware to lug around.
Now, Music Machine turns a C64 into a simple musical keyboard. You play the c-d-e-f… scale on the QWER… keys, c#-d#-f#… on the 235… row respectively, so it’s layed out like a standard piano. There are four different “instruments” to choose from, you can transpose the pitch over five or six octaves and add some cheesy vibrato- or chorus-like effects. There’s also a simple adjustable metronome.

While the screen shows the notes played, it is not necessary to use it at all. So… as we now have this C64 mini-synthesizer not requiring any additional hardware to be used, it would be a shame to have it just stand there on a table while you play it. Of course, as rock credibility requires, you have to wear it.

So, I simply drilled two holes on the left and right side of the case, fastened guitar pins (reinforced on the inside by two pieces of metal, so the plastic case won’t crack when being loaded on it’s own weight) and applied a guitar strap. And because having two cables (power and audio) coming out of your keytar just doesn’t look good, I fitted the C64 with a standard quarter inch guitar connector next to the power connector and made a 6 meter extension cable. It’s a standard Cat. 5 network cable (for the sole reason that I have plenty of that and that it has enough wires, as the C64 power requires four lines plus the two for audio) with two plugs on each end. The C64 power supply and a standard guitar cable leading to the amp are plugged into the remote end.

To be used sometime in the future. Until then, enjoy the dorky picture of me that Till wasn’t afraid to take in the backyard.

Lots of pots

After some weeks away from the workbench I continued working on the keytar. I finished the white “pickguard” area. Now it features three faders on the existing plastic “pickup” dummys and five pots, four of them regular and the fifth one with an additional on/off-switch for the whole setup:

Also, there are in total 18 LEDs in the small holes next to the pickups. The holes already existed and have a diameter of 3mm which made fitting 3mm LEDs quite easy. Apart from that, it somehow takes ages to build all that when you try to make it look good. There are lots of small plastic pieces in the way of the new electronics and so my workspace is completely covered in small plastic debris from sawing, drilling and filing the toy guitar. Cutting the straight slits for the sliders was a special pain in the ass. They ended up almost straight.
Next: Installing the blue LCD in the guitar body and wiring up everything.

Keytar Project:
Part 6: Guitar neck keyboard
Part 8: soon

Guitar neck keyboard

I took some days’ time off from hacking but tonight I wanted to do something, so I assembled the one octave of buttons the guitar neck is going to have.

In the last post, I had the image of the inside of the headstock of the plastic guitar where I fixed six pots (knobs you can turn) in the holes of the tuning pegs. The upper neck area will be fitted with four touch switches (so you can trigger them by just touching them). The lower neck area now has twelve small pushbuttons arranged like piano keys, seven white and five black keys.

To drill the holes at the proper places I first measured the plastic neck case and drew a stencil in Photoshop which I printed, cut out and taped to the case:

I pierced the surface at the twelve hole centers with a screw and a hammer, peeled of the paper stencil and drilled the holes (with a drill bit suitable for wood). I had to dremel away some of the plastic frets around the holes so the buttons would mount flush to the case. I fixed the buttons et voilà:

I’ll still have to connect them, though. They are playable with the left hand reaching around the bottom side of the neck, just like when playing a higher chord on a real guitar. Their purpose will most likely be transposing some kind of musical loop or sequence into other keys or playing chords.

Keytar Project:
Part 5: My desk is covered in cables and stuff
Part 7: Lots of pots

My desk is covered in cables and stuff.

Just two pictures of the progress. The interface is running (and small pizzaboxes are gread ad-hoc cases):

Grey ribbon cables are for lusers. Rainbow colored ribbon cables rock completely. Too bad this is not visible when assembled:

Keytar Project:
Part 4: Soldering
Part 6: Guitar neck keyboard

Soldering

On Monday, the parts for the Midibox arrived from Mike’s Elektronikseite. I ordered the boards and the parts there because it saves a lot of time and is not much more expensive than getting everything from various sources.

It is Wednesday evening now and I’ve been busy soldering all the boards the last two days. I started with one of the easier small boards and did the “core” board last. The digital out board has no resistors yet because of the different LEDs that need different resistance to light up with equal brightness. This is how it looks now. The cables at the right side are power and MIDI in/out.

I am very happy that it works. I uploaded the operating system, MIOS and the Midibox64 application onto the microchip via MIDI and had no problems so far.

Today I bought the rest of the parts I need for my keytar: Pots, knobs, sliders and the small LCD so I can actually start using everything. With the LCD and four menu buttons you can access the complete configuration of the Midibox system.

The next tasks are drilling lots of holes into the plastic guitar, mount all those switches, pots and LEDs and wire everything as well as adapt the Midibox program so that it works for my ideas.

Keytar Project:
Part 3: MIDIbox inside
Part 5: My desk is covered in cables and stuff.

Midibox inside

After 9 hours of usage, my pink test LED has not changed its color, so now I’m happily assuming that the pink will be quite stable.

So now, what actually will be the purpose of my MIDI keytar? First of all, it is only a controller. That means that it will not produce a sound itself, but only control another electronic MIDI instrument such as a synthesizer or a computer with music software. With MIDI, you can send information about what note should be played with which instrument and lots of other parameters. So the keytar will be something like those programmable remote controls for your TV and DVD player, only for music.
It will have buttons that can be pressed, pots that can be turned, sliders that, well, slide, and lots of LEDs that show if something is activated or not. I’ll write a detailed recollection of my ideas for the instrument for the next part of this series of articles.

Time to reveal what will actually go inside the hollow plastic guitar. MIDI is a serial data protocol, so you need some kind of controller circuit to generate a MIDI data stream. You cannot just connect switches or sliders directly to some synthesizer. I have decided to use the very well-documented Midibox64 of the do-it-yourself Midibox platform available on uCApps.de.

Generally, Midibox is a modular system for building your own synthesizers and MIDI controllers. Each application consists of several connected hardware modules and some software running on the project’s own MIOS operating system on a microprocessor which is the core of each system.

The application called Midibox64 is capable of connecting up tp 64 switches, 64 pots and 64 LEDs via MIDI. I will be using 24 switches, 16 pots and 32 LEDs, which is already a lot. This is a complete do-it-yourself project, but I don’t want to start from zero completely, so I will build a fairly standard Midibox64 system using pre-made circuit boards and not try to reinvent the wheel. I have already ordered all necessary boards and electronic components which only leaves me with soldering everything.

Keytar Project:
Part 2: Pink is the new LED
Part 4: Soldering

Pink is the new LED

My first order of parts for the MIDI keytar arrived today: A bunch of LEDs. Of course an electrified guitar has to light up like a fairground, so I’ll have 33 LEDs in total on the guitar.

As the standard red, yellow/amber and green LEDs have been around for over 30 years now and their look is somewhat dated, I ordered pink, blue, cyan and purple LEDs. Hey, I’m hacking a cheap plastic toy, so I’ll just have to do this the cheesy way all along.

The LEDs came from Europkauf, the only seller I found to have 3mm pink LEDs stocked, even though at a premium price, compared to standard LEDs. Something I just found out (and probably should have checked before ordering) is the way that pink LEDs work: They are blue LEDs containing an additional red phosphoric layer that emits red light as soon as the LED is powered. The guy from LED museum has found out that this phosphor layer can be either organic or inorganic. Pink LEDs with organic layers stop emitting their red light after only some hours of operation and turn into substandard blue LEDs.

So I hope that my LEDs are of the inorganic type. I have hooked up one pink LED to my lab power supply and will have it running until tomorrow and then compare it to one of the unused LEDs.

Keytar Project:
Part 1: Building a MIDI keytar
Part 3: Midibox inside

Building a MIDI keytar

Several weeks ago I bought a plastic toy e-guitar on a flea market. The small circuit inside was a defunct amp for an additional plastic microphone. The (remaining) strings were useless steel wires and I doubt that you could ever use it for music (at least not in european harmonic tradition).

I kept the plastic guitar for some unknown future use. Consequently, the future ended about two weeks ago when I decided that it would become a midi controller. Musicians on laptops are way uncool, as Tom from MusicThing pointed out some time ago (check the link at the end of his post). To rock, you need a guitar. Even if you don’t play the guitar.

So, welcome to my little coverage of transforming a plastic toy guitar into a uber-hot MIDI keytar. Yay. It still needs a cool name, though.

Keytar Project:
Part 2: Pink is the new LED