Tiptoe Through The Tulips In No Time With Ukule-LED

December 17, 2014 by Kristina Panos 8 Comments

Take it from someone who has played at the guitar for over 20 years: reading sheet music can be a big stumbling block to musical enjoyment. Playing by ear is somewhat unreliable, tablature only works well if you’re already familiar with the tune and tempo, and pulling melody from chord charts is like weaving fiction from the dictionary. A lot can be said for knowing basic chord formations, but it can be difficult get your fingers to mimic what you see on the page, the screen, or someone else’s fretboard. Enter Ukule-LED, a learning tool and all-around cool project by [Raghav and Jeff] at Cornell.

Ukule-LED uses 16 NeoPixels across the first four positions of the fretboard to teach chord positions. All 16 NeoPixels are connected in series to a single pin on an ATMega1284P, which sits on a board mounted to the bottom of the uke along with power and serial. [Raghav and Jeff] set the NeoPixels below the surface so as not to interrupt playability. The uke can operate in either of two modes, ‘play’, and ‘practice’. In ‘play’ mode, the user feeds it a text file representing a song’s chords, tempo, and time signature. The LEDs show the chord changes in real-time, like a karaoke teleprompter for fingers. In ‘practice’ mode, the user enters a chord through the CLI, and the lights hold steady until they get a new assignment. Knowing which fingers to use where is up to the user.

To add another layer of learning, major chords alight in green, minor chords in red, and 7th chords in blue. These are the currently supported chord types, but the project was built with open, highly extendable Python sorcery available for download and subsequent tinkering. Go on tour after the break.

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Meet Registroid – Mutant Cash Register Music Sequencer

December 15, 2014 by Matt Freund 5 Comments

73 years ago WWII was in full swing, the world’s first computer had not yet crunched atomic bomb physics and department store cash registers had to add up your purchases mechanically. Back then, each pull caused the device to whirl and kerchunk like a slot machine. [David] & [Scott] kidnapped one of those clunkers and forced it to sing a new tune. Thus the Registroid was born, a self-described “mutant vintage cash register that is a playable, interactive electro-house looping machine.” Why did no one else think of this yet?

Inside, the adding gears and tumbling counters were gutted to make room for the electronics, amp and speaker. Keys were converted to Arduino inputs that then feed to MAX/MSP which serves as a basic midi controller. On top, five “antennae” lamps with LEDs serve as a color organ where they pulse with the audio as split up by an MSGEQ7 equalizer chip. Each row of latching keys corresponds to a different instrument: drum beats, baselines, synths, and one-shots.

We have seen similar things done to a Game Boy and typewriter before, but a cash machine is new to us. Perhaps someday someone will flip the trend and type their twitter messages from an antique harpsichord.

The Registroid appears quite popular when on display at local events, including some wonder when a secret code opens the cash drawer.

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Sqonkbox 55 Is A Cigar Box Organ Of Awesome

December 14, 2014 by Kristina Panos 10 Comments

Sometimes, the best birthday presents are the ones you give yourself. In [Dino]’s case, they’re the ones you make for yourself. In honor of his 55th, he built the Sqonkbox 55, a 13-note cigar box organ based on a 555 and amplified with an LM386.

It’s based on a 555 wired in astable mode, turning it into an oscillator that outputs a frequency. This frequency is determined by the resistors between pins 6 and 7, another between 7 and 8, and the capacitor between pin 2 and ground. [Dino] shows a breadboard version first, with a single tuning pot and momentary acting as a piano key. As he explains, this portion of the circuit is repeated 13 times with pots and momentaries that he arranges like piano keys through the lid of a cigar box.

“Sqonkbox,” you ask? A second 555 in astable mode sends the output through an LED. This LED stands face to face with an LDR, and they are shrouded in this configuration with black heat shrink tubing. The ‘sqonk’ 555 changes the frequency of the first 555, providing a clippy, rhythmic tone at the rate set by a potentiometer. [Dino]’s full video of the build is after the break. A BOM is forthcoming, but it’s easy enough to puzzle it out between the video and the lovely, Forrest Mims-esque schematic. Continue reading “Sqonkbox 55 Is A Cigar Box Organ Of Awesome” →

MIDI Keyboard With Frickin’ Laser Keys

December 13, 2014 by Rick Osgood 10 Comments

MIDI instruments are cool, but they’re not laser cool. That is, unless you’ve added lasers to your MIDI instrument like [Lasse].

[Lasse] started out with an old MIDI keyboard. The plan was to recycle an older keyboard rather than have to purchase something new. In this case, the team used an ESi Keycontrol 49. They keyboard was torn apart to get to the ~~creamy center~~ circuit boards. [Lasse] says that most MIDI keyboards come withe a MIDI controller board and the actual key control board.

Once the key controller board was identified, [Lasse] needed to figure out how to actually trigger the keys without the physical keyboard in place. He did this by shorting out different pads while the keyboard was hooked up to the computer. If he hit the correct pads, a note would play. Simple, but effective.

The housing for the project is made out of wood. Holes were drilled in one piece to mount 12 laser diodes. That number is not arbitrary. Those familiar with music theory will know that there are 12 notes in an octave. The lasers were powered via the 5V source from USB. The lasers were then aimed at another piece of wood.

Holes were drilled in this second piece wherever the lasers hit. Simple photo resistors were mounted here. The only other components needed for each laser sensor were a resistor and a transistor. This simple discreet circuit is enough to simulate a key press when the laser beam is broken. No programming or microcontrollers required. Check out the demonstration video below to see how it works. Continue reading “MIDI Keyboard With Frickin’ Laser Keys” →

Tripping On Oscilloshrooms With An Analog Scope

December 13, 2014 by Sarah Petkus 19 Comments

This might be an old trick, but it’s still cool to see a functional tool like the oscilloscope manipulated for an unrelated purpose such as this. [Jerobeam Fenderson] made a video explaining how to input stereo audio into an old digital scope in order to create of all things, dancing mushrooms… because why not?

In this case, [Jerobeam] used a Tektronix D11 5103N set in X Y mode and attached the left and right channels from his RME Fireface UC audio interface. One channel corresponds with X, and the other with Y. From here, he controls the wave forms discretely with the help of software like Pure Data (Pd) and Max (not free, but more powerful) which are visual programming environments made to enable musicians and artists to create software without writing lines of code. His video explains how to make a circle out of a sine wave, and then beat the crap out of it with math far beyond our comprehension. The outcome is pretty mesmerizing and leaves us wanting to try it out ourselves. Luckily, if you’re interested in experimenting with the voice of sine waves… [Jerobeam] has more information on his blog on how to do some scope play of your own whether your hardware is analog or digital.

You can see the dancing mushrooms in his video below:

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Mixer For Korg Volcas

November 30, 2014 by Brian Benchoff 5 Comments

Korg, everyone’s third or fourth favorite synth company, but one of the only ones that still in business, recently put out a new line of synths, drum machines, and groove boxes. They’re called Volcas, and they’re cheap, analog, and very cool. [Jason] has a few of these Volcas, and while he enjoys the small form factor, using an off-the-shelf mixer to dump send the audio from these machines to his computer takes up too much space. He created a passive mini mixer to replace his much larger Mackie unit.

The circuit for this tiny passive mixer is an exercise in simplicity, consisting of just a few jacks, pots, and resistors. [Jason] overbuilt this; even though the Volcas only have mono out, he wired the entire mixer up for stereo.

The enclosure – something that looks to be a standard Hammond die cast aluminum enclosure – was drilled out, and a lovely laser cut acrylic laminate placed on top. It looks great, and for anyone interested in learning soldering, you couldn’t come up with a better first project.

A 16-voice Homebrew Polyphonic Synth

November 26, 2014 by Brian Benchoff 11 Comments

Homebrew synths – generating a waveform in a microcontroller, adding a MIDI interface, and sending everything out to a speaker – are great projects that will teach you a ton about how much you can do with a tiny, low power uC. [Mark] created what is probably the most powerful homebrew synth we’ve seen, all while using a relatively low-power microcontroller.

The hardware for this project is an LPC1311 ARM Cortex M3 running at 72 MHz. Turning digital audio into something a speaker can understand is handled by a Wolfson WM8762, a stereo 24-bit DAC. Both of these chips can be bought for under one pound in quantity one, something you can’t say about the chips used in olde-tyme synths.

The front panel, shown below, uses 22 pots and two switches to control the waveform, ADSR, filter, volume, and pan. To save pins on the microcontroller, [Mark] used a few analog multiplexers. As far as circuitry goes, it’s a fairly simple setup, with the only truly weird component being the optocoupler for the MIDI input.

The software for the synth is written mostly in assembly. In a previous version where most of the code was written in C, everything was a factor of two slower. Doing all the voice generation in assembly allowed for twice as many simultaneous voices.

It’s a great project, and compared to some of the other synth builds we’ve seen before, [Mark]’s project is at the top of its class. A quick search of the archives says this is probably the most polyphonic homebrew synth we’ve seen, and listening to the sound sample on the project page, it sounds pretty good, to boot.