Heavy Metal Detectors

Helsinki has a strong underground Heavy Metal scene, so what better way to show it off than to have listeners literally unearth the local sounds themselves with converted metal detectors that play, naturally, Metal? [Steve Maher] built these modified detectors and handed them to a bunch of participants who went on exploratory walks around the city. The tracks from local bands changed as the user moved from one concealed metallic object to the other to create the experience of discovering the hidden soundscape of the land.  Continue reading “Heavy Metal Detectors”

An Interactive Oasis At Burning Man

An oasis in the desert is the quintessential image of salvation for the wearied wayfarer. At Burning Man 2016, Grove — ten biofeedback tree sculptures — provided a similar, interactive respite from the festival. Each tree has over two thousand LEDs, dozens of feet of steel tube, two Teensy boards used by the custom breath sensors to create festival magic.

Grove works like this: at your approach — detected by dual IR sensors — a mechanical flower blooms, meant to prompt investigation. As you lean close, the breath sensors in the daffodil-like flower detect whether you’re inhaling or exhaling, translating the input into a dazzling pulse of LED light that snakes its way down the tree’s trunk and up to the bright, 3W LEDs on the tips of the branches.

Debugging and last minute soldering in the desert fixed a few issues, before setup — no project is without its hiccups. The entire grove was powered by solar-charged, deep-cycle batteries meant to least from sunset to sunrise — or close enough if somebody forgot to hook the batteries up to charge.

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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.

A Full Speed, Portable Apple //e

A while back, [Jorj] caught wind of a Hackaday post from December. It was a handheld Apple IIe, emulated on an ATMega1284p. An impressive feat, no doubt, but it’s all wrong. This ATapple only has 12k of RAM and only runs at 70% of the correct speed. The ATapple is impressive, but [Jorj] knew he could do better. He set out to create the ultimate portable Apple IIe. By all accounts, he succeeded.

This project and its inspiration have a few things in common. They’re both assembled on perfboard, using tiny tact switches for the keyboard. The display is a standard TFT display easily sourced from eBay, Amazon, or Aliexpress. There’s a speaker for terribad Apple II audio on both, and gigantic 5 1/4″ floppies have been shrunk down to the size of an SD card. That’s where the similarities end.

[Jorj] knew he needed horsepower for this build, so he turned to the most powerful microcontroller development board he had on his workbench: the Teensy 3.6. This is a 180 MHz ARM Cortex M4 running a full-speed Apple IIe emulator. Writing a simple 6502 emulator is straightforward, but Apple IIe emulation also requires an MMU. the complete emulator is available in [Jorj]’s repo, and passes all the tests for 6502 functionality.

The project runs all Apple II software with ease, but we’re really struck by how simple the entire circuit is. Aside from the Teensy, there really isn’t much to this build. It’s an off-the-shelf display, a dead simple keyboard matrix, and a little bit of miscellaneous circuitry. It’s simple enough to be built on a piece of perfboard, and we hope simple enough for someone to clone the circuit and share the PCBs.

Vintage Laptop Keyboard Types Again Through USB

Have you ever had a laptop you just wish you didn’t have to retire when its specification becomes to aged for your needs? Wouldn’t it be great if you could upgrade it and keep using the physical hardware!

[Alpinedelta] has a vintage Toshiba T1000 laptop, roughly a PC-XT clone from the late 1980s. Its 80C88 processor, CGA display, and 512k of memory make it a museum-piece, but he has plans to modernise it using a LattePanda Intel Atom based single board computer.

To make that happen, he has to ensure all the Toshiba’s peripherals will talk to a modern host. Unfortunately back in the 1980s many PC clones were clones in a rather loose sense, and especially so in the laptop arena. Thus there are no handy standard PC interfaces and since USB was several years away at the time, nothing the LattePanda can talk to directly. His solution for the keyboard is to wire its matrix directly to a Teensy microcontroller that then provides a USB interface, and he’s put up a useful step-by-step Instructables guide.

There is no standard for a laptop keyboard matrix, so the first and most tedious task is to unpick its layout.This he did by identifying each trace and assigning a different rainbow colour to it, before noting down which keys appeared on it and collating the results in a spreadsheet. The different colours of wire could then be assigned to the colours of a piece of rainbow ribbon cable, and wired in sequence to the Teensy’s I/O pins. There then follows a step in the software in which he assigns the pin mappings to the lines in his spreadsheet, then the sketch can be compiled and uploaded to the Teensy. Result: a vintage keyboard now talking USB.

Using a Teensy to present a USB keyboard to the world is a well-worn path, we’ve seen it with both newer keyboards and other relics like this one from a DEC VT100.

Thanks [Brent] for the tip.

Robo-Flute Whistles MIDI

We aren’t sure this technically qualifies as music synthesis, but what else do you call a computer playing music? In this case, the computer is a Teensy, and the music comes from a common classroom instrument: a plastic recorder. The mistaken “flute” label comes from the original project. The contraption uses solenoids to operate 3D printed “fingers” and an air pump — this is much easier with a recorder since (unlike a flute) it just needs reasonable air pressure to generate sound.

automated-recorder-solenoid-driverA Teensy 3.2 programmed using the Teensyduino IDE drives the solenoids. The board reads MIDI command sent over USB from a PC and translates them into the commands for this excellent driver board. It connects TIP31C transistors, along with flyback diodes, to the solenoids via a terminal strip.

On the PC, a program called Ableton sends the MIDI messages to the Teensy. MIDI message have three parts: one sets the message type and channel, another sets the velocity, and one sets the pitch. The code here only looks at the pitch.

This is one of those projects that would be a lot harder without a 3D printer. There are other ways to actuate the finger holes, but being able to make an exact-fitting bracket is very useful. Alas, we couldn’t find a video demo. If you know of one, please drop the link in the comments below.

We have seen bagpipe robots (in fact, we’ve seen several). We’ve also seen hammering shotguns into flutes, which is certainly more melodious than plowshares.

MIDI DAC for Vintage Synth Hacks

A lot of classic synthesizers rely on analog control voltages to vary parameters; this is a problem for the modern musician who may want to integrate such hardware with a MIDI setup. For just this problem, [little-scale] has built a MIDI-controllable DAC for generating control voltages.

It’s a simple enough build – a Teensy 2 is used to speak USB MIDI to a laptop. This allows the DAC to be used with just about any modern MIDI capable software. The Teensy then controls a Microchip MCP4922 over SPI to generate the requisite control voltages. [little-scale]’s video covers the basic assembly of the hardware on a breadboard, and goes on to demonstrate its use with a performance using the MIDI DAC to control a Moog Mother 32 synth. [little-scale] has also made the code available, making it easy to spin up your own.

We can see this project being indispensable to electronic musicians working with banks of modular synths, making it much easier to tie them in with automation in their DAW of choice. This isn’t the first MIDI interfacing hack we’ve seen either – check out this setup to interface an iPad to guitar pedals.

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