Analog Drum Machine

December 17, 2013 by Eric Evenchick 11 Comments

This analog drum machine project synthesizes a kick and snare drum that are clocked to a beat. It pulls together a few analog circuits to do the timing and synthesis.

The beat timing is a product of a hysteretic oscillator used to create a ‘shark wave,’ which is a friendly term for the output of a relaxation oscillator. This waveform can be compared to a set point using a comparator to create a slow square wave that clocks the drum beat.

The kick drum is synthesized using another hysteretic oscillator, but at a higher frequency, creating a triangle-like waveform at 265 Hz that provides a bass sound. The snare, however, uses white noise provided by a BJT’s P-N junction, which is reverse biased and then amplified. You can spot this transistor because its collector is not connected.

The resulting snare and kick drum wave forms are gated by two transistors into the output. Controlling these gates allows the user to create a drum beat. After the break, check out a video walk-through and a demo of the build.

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Cast A Shadow, Play A Note

December 15, 2013 by Kristina Panos 3 Comments

Looking for a way to entertain friends and family this holiday season? Look no further than the Arduino-powered Photocell Piano. [Asahillis] has posted this Instructable for building a 6-note musical command center.

The piano uses photoresistors to turn each note on when the player runs their hand over it. Notes can be tuned independently using potentiometers on the front of the box. The hack uses two circuits: one to generate the tones, and a second to mix them. [Asahillis] adapted [Forest Mims III]’s timeless schematics for the 555 Tone Maker and the 741 Audio Mixer to create his Photocell Piano.

When the instrument is powered on, the code takes a 5-second reading of the ambient light, and sets a threshold based on its findings. Afterward, the first note will sound, indicating the piano is ready to be played. Each note has its own if-else statement that tells it to sound when its corresponding photoresistor reaches a value below the set threshold (when the player casts a shadow). ~~There’s a demo video included in the guide but we couldn’t embed it here.~~ Check out the demo video after the break.

If you prefer to rock out with your lights out, there’s always this impressive laser harp.

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Portable Musical Stairs

December 13, 2013 by James Hobson 8 Comments

[Amir] recently finished a pretty cool project — Portable Musical Stairs! He designed and built it so it could be temporarily installed in schools for musical therapy sessions with autistic children — a fun activity for all ages!

The system utilizes lasers and photo sensors that come with a built in digital output with a sensitivity potentiometer, which makes it super easy for the Arduino Leonardo to interpret. The reason they are using 2 by 4’s for the system is because of the width of the stairs. At 1.75m across, a laser misaligned by only 1 degree results in it being about 3cm off!

On the software end of things, the Arduino acts as a HID input to the computer to create the sounds. [Amir] has put together a free sound sampler on his website makeysoundy.com, and we must say, it’s pretty fun! You can assign notes to different keys, which makes it super easy to make a similar project to this!

Stick around after the break to see the stairs in action!

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The 3D Printed Ukulele

December 11, 2013 by Brian Benchoff 18 Comments

uke

The creator of everyone’s favorite slic3r – [Alessandro Ranellucci] – has been hard at work putting his 3D modeling skills to the test. He’s created a ukulele that’s nearly entirely 3D printed (Google translation). Everything on the uke, short of the strings and tuning pegs came from a MendelMax 3D printer, all without any support material at all.

In the video, [Alessandro] and uke virtuoso [Jontom] show off how this instrument was put together and how good it can sound. The body of the uke is made of two parts, and the neck – three parts including the headstock and fretboard – all fit together with surprisingly traditional methods. A dovetail joint connects the neck to the body and a tongue and groove-like joint holds the headstock to the neck.

[Allessandro] puts the print time of all the uke parts at ~~about 120~~ under 20 hours and about 20 Euros worth of plastic. As far as ukuleles go, this sounds just as good as the average instrument, but [Jontom] says the action is a little bit high. That’s why files were invented, we guess.

Thanks [iant] for sending this one in.

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LavaAMP Spectrum Analzyer

December 4, 2013 by James Hobson 15 Comments

lavaamp

Is your dusty Lava Lamp just not cool enough anymore? What if you could make it bubble to the music? [Christian] and [Eric] managed to do just that.

No, they aren’t regular Lava Lamps. In fact, they look like oversize jam jars, but the video of them in action is pretty cool! They designed and built this system for the UIST 2013 Student Innovation Contest, and while there isn’t too much information on the actual build, the contest required everyone to use the exact same kit. The kit consists of 8 aquarium pumps, a PumpSpark controller board, assorted tubing and fittings and an optically-isolated serial interface for use with an Arduino or another kind of microcontroller. From there, it’s pretty easy to guess the rest — analyzing the audio, and timing the pumps according to the various levels.

Other competition entries of note include an awesome game of WaterPong, a Water Bottle Bagpipe, and even an Xbox H2O!

Stick around after the break to see the LavaAMP bubble to the bass.

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Improving A Cheap Guitar Pedal

November 29, 2013 by Brian Benchoff 12 Comments

pedul

If something doesn’t suit your needs, just change it. That’s a motto we live by, and it looks like [Doug] took up the same creed when he modified a cheap effects pedal.

The victim of [Doug]’s soldering iron is a Danelectro BLT Slap Echo – a tiny, cheap pedal in Danelectro’s mini ‘food named’ pedal series. Stock, this pedal’s slap back echo is set to a fixed amount of time. [Doug]’s mod changes that.

The mod consists of desoldering a single SMD resistor and replacing that with a 50k pot [Doug] had lying around. After mounting the pot between the two stock knobs, the new and improved pedal had a variable length echo. There are a few more mods possible with this pedal – changing some of the resistors on the filter for a better sound, or even connecting the rate pot to a wah-style rocker pedal for some wobbly Echoplex or Space Echo action.

You can check out [Doug]’s gallery of pics here.

A Modular Game Boy Synthesizer

November 27, 2013 by Brian Benchoff 10 Comments

Euro

Synth heads and electronic music aficionados the world over love a good rackmount synth. These days, though, synthesis tends more toward small, digital, and ‘retro’ rather than the monstrous hulking behemoths of the 60s and 70s. [gieskes] might be ahead of the curve, here, as he’s built a Game Boy module for his eurorack synthesizer.

The software running on [gieskes]’s Game Boy is the venerable Little Sound DJ (LSDJ), the last word in creating chiptunes on everyone’s favorite 8-bit handheld. As with any proper Game Boy used in chiptunes, there are a few modifications to the 1980s era hardware. [gieskes] tapped into the cartridge connector with a ‘repeat’ signal that provides slowed down, noisy signals for LSDJ. There’s also pitch control via CV, and the audio output is brought up to 10Vpp

In the video below, you can see [gieskes]’ euroboy in action with a few Doepfer synth modules. There’s also a very cool pulse generator made from an old hard drive in there, so it’s certainly worth the watch.

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