Atari Punk Stick Puts A Synth In A Joystick

November 7, 2012 by Brian Benchoff 8 Comments

[youtube=http://www.youtube.com/watch?v=ngXrTd-8jf4&w=470]

The Atari Punk Console, a tiny synthesizer based on the ubiquitous 555 timer chip, is the first build de rigueur for any budding electronic wizard wanting to build musical devices. With just a handful of caps, resistors, and a pair of pots, the APC is a fabulously fun and easy build made even cooler by [Pat]’s addition of a joystick.

The circuit of the Atari Punk Console consists of a 556 chip – basically two 555s put into the same package – and a pair of potentiometers to control the frequency and output of this very basic synth. Since most joysticks are just two pots arranged on an X-Y mount, [Pat] thought it would be cool to control his APC without twiddling knobs, and instead sweeping a joystick around.

After acquiring an old Microsoft joystick from his local Goodwill, [Pat] wired up his Atari Punk Console to the joystick, using the ‘fire’ button to turn the output on and off. The result is everything between a low machine gun-like tone to a nasal square wave that will hopefully keep pace with your chip-based audiophile friends.

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MR-808 Is A Mechanical Version Of The Most Famous Drum Machine

November 5, 2012 by Brian Benchoff 27 Comments

Anyone who has listened to any music from the 80s has heard the percussive effects of the infamous TR-808 drum machine. To the modern ear, it sounds like an antique. Being the most popular drum machine of all time means it must have some redeeming qualities, right?

[Moritz Simon Geist] decided he wanted nothing to do with the wimpy computer-based emulations of a TR-808. Instead, he chose a more mechanical version that puts robots inside a gigantic 808 enclosure to play snares, high hats, cowbells, and drums in time with any MIDI drum track.

[Moritz] calls his build the MR-808 and puts a real-life bass drum, snares, hats, toms, claps, and a ride into a 3.3 x 1.7 meter ( 10.8 x 5.5 foot) case. The sound triggers are handled by Max/Msp communicating with a pair of Arduinos to handle the solenoids and light effects. You can read more about the hardware setup in [Moritz]’ behind the scenes look.

After the break you can see the MR-808 in action, both alone and by providing the percussion for [Moritz]’ band. A very cool build that now cries out for an Arduinofied bassist placed into an overgrown TB-303 enclosure.

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ATmega1284 As An 8-voice 32 KHz Synthesizer

November 2, 2012 by Mike Szczys 10 Comments

A couple of things strike us about this 8-voice 32 kHz synthesizer. First is the cleanliness of the prototype. As you can see, each part has plenty of room on its own board and all are interconnected by 10-pin IDC ribbon connectors. But you’ll have to see the video after the break to enjoy the impressive sound that this puts out. You’ll hear it play the Super Mario Bros. theme; it does it with passion!

To get audio from the digital microcontroller [Mike] built his own R2R digital to analog converter. The resistor ladder is built from sixteen resistors, which feed a rail-to-rail amplifier. The sound is mono but the playback is polyphonic thanks to the work done by the ATmega1284. It is reading MIDI commands coming in from an external controller (we assume it’s the computer on which the hardware is sitting). The chip’s 128 KB of Flash memory leave plenty of room to store samples, which are selected from a lookup table based on the MIDI data. If more than one sample is to be played the chip averages the data and sets the 8-bit output port accordingly.

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Homebrew Guitar Tuner Also Includes MIDI Out

October 27, 2012 by Brian Benchoff 9 Comments

A few years ago, [Frédéric]’s brother in law wanted a guitar tuner for Christmas. Instead of going out and buying one, [Frédéric] broke out the soldering iron and built one from scratch.

[Frédéric]’s tuner is built around an ATMega168 uC on a Real Bare-Bones Board with an LM386 amplifier. The display is a standard 20×2 LCD character display, and the interface is torn from the pages of stomp box schematics with a very hefty foot switch.

Detecting the frequency of a note played into [Frédéric]’s tuner involves a fair bit of math. To measure the frequency, the Arduino samples the waveform coming from the input jack. This signal is delayed for a fraction of a second and the area underneath the real and delayed waveforms is measured. This delay slides across the original waveform until the area between the real and delayed samples are minimized. At that point, delayed wave form will be exactly one cycle behind the real signal, and the cycles per second can be calculated. It’s called the YIN algorithm, and you can read more about it here.

Since [Frédéric] already knew the exact frequency being played into the tuner, he figured it would be trivial to add a small analog audio to MIDI converter. This feature (as shown in the video after the break) turns the sounds from a guitar into MIDI notes. It’s monophonic and probably a little superfluous, but still very cool.

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Draw Your Own Vinyl Beats

October 26, 2012 by Mike Szczys 13 Comments

The Dyskograf lets you make music with a magic marker. The musical installation looks much like a turntable for playing vinyl records. But instead of a spiraling groove containing the sounds, this uses marks on a paper disk to play sound samples.

You can see the light outline of several tracks on the paper disc shown above. By adding black marks the optical input of the Dyskograf knows when to start and end each sound. This is best illustrated in the video demonstration after the break.

The marker-based setup makes a lot of sense, and we think it would be perfect if the disc was a dry-erase board. It certainly makes it a lot easier to lay down new beats than this other optical turntable which required holes to be drilled in a vinyl record to play the sounds. While we’re on the topic you may also find this coin-based turntable sequencer of interest.

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Typing With A MIDI Drum Set

October 25, 2012 by Brian Benchoff 7 Comments

[Autuin] picked up the drums at the age of 18, but by his own admission he’s no [Bonzo], [Buddy Rich] or [Ringo]. Practicing always seems to fall off the end of his to-do list, and there really is only one way to Carnegie Hall. One thing [Autuin] is really fast at is typing, so he figured he could improve his drumming skills by banging a few paragraphs out.

The core of the build is a Yamaha DTX drum module, a MIDI-to-USB adapter, and little light coding. Basically, [Autuin] made a chorded keyboard out of his drums; by hitting one (or two, or three) drum heads at the same time, he can type characters in Open Office.

For going outside the comfort zone of a steady rock beat, we’re thinking [Autuin]’s build might just be useful. He’ll be displaying his Keyboard/Drum mashup at Vancouver’s East Side Culture Crawl alongside a horrible device of artistic merit. If you promise not to break anything, drop in on him in a few weeks.

Vidia after the break.

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A Harpsichord That Plays Itself

October 19, 2012 by Mike Szczys 20 Comments

[Malcolm Messiter] is an Oboe player who loves to play pieces from the Baroque era. This often means playing with a Harpsichord and he managed to acquire one to call his very own. Unfortunately you can’t play both instruments at once so he set out to automate the keyboard. What you see here is a fully working version, but he soon went on to add solenoids to the upper rank as well. His story starts on page 27 of this newsletter (PDF).

He really went out of his way to make sure the instrument was not mistreated. A cabinet-maker built some brackets to mount the system above the keys. A friend drilled and tapped a sheet of acrylic to which each solenoid was mounted. The solenoid shafts have each been padded with felt to cushion the blow on the keys. We’ve embedded two demo video after the break that show off the first and second versions of the builds.

Harpsichords pluck the strings instead of hitting them with a hammer as the piano does. The mechanism that does the plucking had worn out on many of the keys so [Malcolm] used a 3D printer to help replace them.

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