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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