Teensy Laser Harp Has Big Sound

[Johan] has slipped down the rabbit hole of making musical instruments. His poison? Laser harp MIDI controllers. Having never made one before, he thought he would start small and then iterate using what he learned. Fortunately for us, [Johan] documented the process over on .io, essentially creating a step-by-step guide for building a simple but powerful 16-note laser harp.

Laser Harp I is built around a Teensy 3.2 and, of course, lasers pointed at LDRs. [Johan] used fairly low-power laser modules, which are slightly less blinding if you accidentally look at them for a second, but should still be taken seriously. He added four potentiometers to control the sensitivity, scale, octave, and the transposition. The sensitivity pot essentially accounts for the ambient light in the room. Although it only has 16 notes, Laser Harp I is ready to rock with over 30 different scales to choose from. Check out the brief demo that [Johan] put up on his Instagram.

If you try to build your own laser harp and get lost trying to follow [Johan]’s instructions, don’t worry. His well-commented code and lovely schematic will undoubtedly save you. Then you can move on to open-beam designs.

Marvelous MIDI Button Box

Most DJ tools are just ripe for DIY rework. Everything at least speaks MIDI, and the firmware side of the equation that makes a physical interface for your laptop can be downloaded and flashed with minimal effort. And this means that there’s no time better than the present to wire up a ton of buttons to a Teensy and call it a controller.

[UmamiFish]’s build goes the extra mile, though, with a nice laser-cut box and holes for display LEDs as well as the 22 arcade buttons that are packed tightly into the enclosure. A 74HC595 shift-register IC handles the LEDs, but there’s no getting around a bunch of wiring in a build like this. It pays to be neat, and using ribbon cable helps keep some of the chaos under control.

Browsing around Instructables will turn up myriad similar controllers, should the exact configuration of this one not suit your needs. And if you want something with a little more of the real-disk feel, have a look at this controller that uses hard disk platters, or this log of a timecode-vinyl-to-MIDI build.

Forgotten Rock Band Drum Controller as a MIDI Instrument

Happen to have an old Rock Band drum controller collecting dust in your living room? If you also have a spare Arduino and don’t mind parting with that plastic college memento then you’ve got the bulk of what could potentially be your new percussive MIDI instrument. In his project video [Evan Kale] outlines the steps necessary to turn that unloved plastic into a capable instrument for recording.

The whole process as outlined by [Evan] in under seven minutes. This looks like a great weekend endeavor for those of us just starting out with MIDI. After cracking the back of the Guitar Hero drum kit controller open, the main board within is easily replaced with a standard sized Ardunio (which matches the present mounting holes exactly). About 4:50 into the video [Evan] explains how to add a basic perf-board shield over the Arduino which connects the piezo sensors in each of the drum pads to the analog pins of the micro-controller. The MIDI jack that comes built into the back of the kit can also be reused as MIDI out when wired to the Arduino’s serial out pin. By adjusting [Evan’s] example code you can dial in the instrument’s feedback to match the intensity of each hit.

The video with all of the details is after the jump. Or you can check out a MIDI hack that goes the other way and uses a drum kit as a Guitar Hero or Rock Band controller instead

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Pendulum MIDI Controller Really Swings

Once in a while, we see a project that makes us want to stop whatever we’re doing and build our own version of it. This time, it’s Modulum, a pendulum-based MIDI controller. It’s exactly what it sounds like. The swinging pendulum acts as a low-frequency oscillator. In the demo video configuration, you can hear it add a watery, dreamlike quality, sort of like a lap steel guitar on LSD.

The pendulum’s motion is detected by four pieces of stretchy, conductive cord. These are wired to an Arduino Nano in a voltage divider fashion. [Evan and Kirk] used the Maxuino library to determine x and y mapping of possible pendular positions as well as perform the necessary MIDI processing. Get your groove on after the break, and check out some of the many other fantastic MIDI controllers we’ve had the pleasure of covering.

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The Hard Drive MIDI Controller

[shantea] builds MIDI controllers, and after a successful first endeavor with a matrix of buttons and knobs, he decided to branch out to something a little bit cooler. It’s called Ceylon, and it’s effectively a turntable controller built from an old hard drive.

As a contrast to the first MIDI controller, this would be a stripped-down build, with just three faders, LEDs for eye candy, a pair of pots for gain control, and a hard disk surrounded by six anti-vandal buttons. The hard disk is the star of the show, acting as a rotary encoder.

When manually spun, the hard disk generates a few phases of sinusoidal waves. The faster you spin it, the higher the amplitude and frequency. These signals are far too weak to be sampled directly by a microcontroller, and for digital control – as in, MIDI – you don’t need to read the analog signals anyway. These signals were turned digital with the help of an LM339 quad comparator. With two of these comparators and signals out of the hard disk that are 90 degrees out of phase, quadrature encoding is pretty easy.

The software for this MIDI controller is based on the OpenDeck Platform, a neat system that allows anyone to create their own MIDI controllers and devices.  It’s also a great looking board that seems to perform well. Video below.

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A Custom Control Surface for Audio/Video Editing

Control surfaces (input devices with sliders, encoders, buttons, etc) are often used in audio and video editing, where they provide an easy way to control editing software. Unfortunately even small control surfaces are fairly expensive. To avoid shelling out for a commercial control surface, [Victor] developed his own custom control surface that sends standard MIDI commands which can be interpreted by nearly any DAW software.

[Victor]’s control surface includes several buttons, a display, and a rotary encoder. His firmware sends MIDI commands whenever a button is pressed or the rotary encoder is turned. [Victor] plans on adding menu functionality to the currently unused LCD display which will allow the user to change the scrubbing speed and other various settings.

One advantage of making your own control surface is that you can customize it to your own needs. [Victor] has posted a model of his 3d-printed enclosure and his source code on the project page so you can easily modify his design with any button configuration you might want.

The 128 Button, 6 Axis, 17 Slider, 4 POV Hat Switch Joystick Controller


[Paul Stoffregen], creator of the Teensy series of dev boards, previously implemented a six-axis joystick for Teensyduino, the Arduino library for the Teensy. He had originally tried 8 axes, but a few problems cropped up, deadlines approached, and he left it as is. A few recent projects gave him some insight into how to implement a joystick with more than six axes as a USB HID device, so he started looking at how to read an improbable amount of pots and buttons for a USB joystick.

So far, the biggest problem is figuring out what software can actually use an HID joystick with this many controls. The answer to that question is none. The Linux-based jstest-gtk is able to read 6+17 pots, the four hat switches, but only 64 of the 128 buttons. A user on the Teensy forums, [Pointy], has been working on his own joystick test app that works on Linux Windows, but testing the joystick on Windows is an exercise in futility for reasons no one can figure out.

As for why anyone would want a six-axis, 17-slider, 128-button joystick, think about this: with this much control, it would be relatively simple to build the MIDI controller to end all MIDI controllers, or a cockpit simulator for everything from a C172, 737, to a Kerbal interplanetary cruiser. That’s an impressive amount of control, and all from a $20 Teensy dev board.

Further testing of this Teensy joystick is desperately needed, so if you’re able to help out drop a note in the forum thread.