Build Diary for basic DIY Midi Instruments

[Alistair Hutton]

I've been bitten by the bug and have decided to build a "Tiny Midi Brawler"

Tiny as it's based on the Teensy LC - https://www.pjrc.com/teensy/teensyLC.html which is almost comically small and very cheap. It can active a as a fully class compliant Midi device which makes development an absolute breeze
Midi as that's what it will be outputting
Brawler as it's going to be an unsophisticated Midi Fighter [strike]rip-off[/strike]/homage

This project involves the barest minimum amount of soldering and I now realise that if you buy the Teensy LC with presoldered header pins and a crimping tool then you could do this whole thing without touching a soldering iron.

The basic design idea is a 152mmx152mmx100mm box with a 4x4 grid of buttons and USB midi out via the Teensy. Hardware wise that's it. I was going to put a bit of effort into the software side of things to make the buttons highly configurable (so one button cords/arpeggiations that sort of thing would be possible) via a custom computer program.

Once I've got this done then my next plan is to build a "Teensy Unorderenator" a controller surface with 4 buttons, 4 push button rotary encoders, 2 faders and a Nintendo DS touchscreen for cut price Kaosillator action or a Teensy/SN76489 "synth"

I'll post some initial photos and logs later today or tomorrow.

[zestoi]

sounds pretty interesting i love coding but hardware scares me so ive never tried anything like that

[Alistair Hutton]

sounds pretty interesting i love coding but hardware scares me so ive never tried anything like that

This is my first hardware project (beyond making an Arduino blink a LED and building a really simple Lunetta on a bread board ( http://electro-music.com/forum/forum-160.html for those interested in the fascinating world of Lunettas) )

The apeal of this project is how simple the hardware is to do - I am rubbish at soldering but the soldering for this is so basic that it well within my capabilities and as I said if I'd invested in a crimping tool then this project would have been solder free, just plugin wires into sockets.

[Alistair Hutton]

So the key components are

The Teensy LC



This is a lovely little microcontroller system that can be had for just $11.65. I've soldered header pins onto it to make it easier to connect up the wires. I need just 16 pins and this has 27 so plenty to spare - I could eaily add all kinds of extra buttons and pots to this but I'm keeping it simple for now.



Notice how I use artful depth-of-field effcts to hide my terrible soldering job on the other side. You can get the Teensy with header pins pre soldered for $14.65

The Buttons



Sanwa OBSF-24's these are not. My aim is cheapness. If you go on E-bay and search for OBSF-24 you'll find plenty of Chinese manufacturers who will be happy to sell you perfectly decent OBSF-24 like buttons in lots of 10 for $9.99 which makes this whole endeavour very reasonably priced.

They actually have a really nice action for the price, the *click* is very loud so silent operation this is not but they do have the all important gently convex surface to allow easy movement of fingers across the buttons.

[DJDoubleYou]

Ha funny, it's exactly the opposite with me, love the hardware but coding is not my strong suit. I will however be building a DIY controller to control the effects in Traktor soon, i'll start a thread too once I receive all the stuff I ordered.

[Alistair Hutton]

I just got a pair of SN76489 chips delivered - they are the sound chips used in the Master System, lots of old arcade games and the like. It is comically trivial to get a sound out of it as it defaults to emitting a nice low bass note on power up. you literally just need to wire a 4Mhz clock to it and apply power and it sends out an audio signal.

My plan is to wire up two of them to a Teensy and use them as a 6 voice Midi device - the Teensy can read Midi messages as well as send them so I could connect both my Teensy Midi Brawler and SN76489 synth and use the brawler to play the dual SN76489s. That will definitely be my next project after I finish the Brawler.

[Alistair Hutton]

I bought myself a crimping tool to reduce the amont of soldering I have to do but having crimped a quarter of all the connectors I need I can't help but thing it would have been easier to solder the connections.

However if I have any problems with individual wires it will be way easier to disconnect the crimped wire than having to desolder joints.

I've ordered my case (went for a custom laser cut box as I don't have the wood working tools to drill wholes I need myself. So I am just waiting for it to arrive and then I'll put the thing together.

[Alistair Hutton]

Half way through crimping all my cables.

Found out it's up to 28 days to get my box laser cut and delivered so the Tiny Midi Brawler is on hold till then. Will invest some more time in putting together my mini synth while waiting for the box.

[Alistair Hutton]

While I wait for my proper case to come I bodged together some corrugated cardboard.


Behold the wonder:

[DJDoubleYou]

Hey just one quick question, i've been modding the DJTT Sanwa buttons to cut the length in half but it is a ton of work. How tall are these buttons? And how does their "feel" compare to the DJTT Sanwa's?