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ArduTouch Puts Way-Cool Sounds in Your Hand

David Battino

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In this month’s “Bat Utility Belt,” columnist David Battino solders up a fuzzy little synth that delivers unique sounds for less than $30 (video above).

It’s oddly satisfying to learn that Mitch Altman, inventor of the keychain remote that silences other people’s TVs, also designed a sweet little synthesizer. You may remember his TV-B-Gone as the gadget that got a mischievous tech blogger banned for life from the Consumer Electronics Show. Altman’s ArduTouch is a DIY synth based on an Arduino-compatible chip. It’s an ideal project for beginning makers, yet deep enough for more adventurous musicians. And if you’re curious, as I was, to explore Arduino programming, you can dive right in thanks to the included ArduTouch synthesis library.

The lavishly illustrated assembly guide (PDF) is easy to follow—probably the friendliest DIY directions I’ve seen. (As Altman recounts in this TED talk, he travels the world teaching people how to build electronic projects, and his love for makers shows.) Best of all, the ArduTouch gives you loads of unique sounds for just $29.99, making it another great fit for the Bat Utility Belt series.

Figure 1: The ArduTouch kit has just a handful of parts; its personality comes from the variety of synth “sketches” you can load over USB. 

Ardu Experienced?

Arduino is a hardware/software platform designed to help people build interactive electronic projects. For the ArduTouch, Altman combined an Arduino Uno clone with an amplifier chip and a capacitive-touch keyboard. (He was inspired by the Stylophone.) Other controls include two buttons (plus a reset button) and two knobs.

The kit comes with a small monophonic speaker and a 3.5mm stereo audio output jack. In this video clip, I’m playing the pre-installed Thick softsynth through external stereo speakers. Thick features four layered sawtooth waves tuned to fifths and octaves, with different portamento on each. The knobs adjust the portamento speeds. The red buttons switch octaves when clicked, or alternate between unison and spread tuning when held.

“Ironing out” my ArduTouch with the Thick softsynth. I attached the speaker with longer wires so I could mount it in the lid of this GPS case.

Building It

Don’t be afraid if you’ve never soldered; the assembly manual is lovingly detailed. There’s even a link to Altman’s free Soldering Is Easy comic book. I assembled my ArduTouch in about an hour. 

After playing with it for a while, I made two changes. First, I Velcroed the AA battery pack to the bottom of the circuit board to make the synth self-contained. Next, I replaced the speaker wires with header pins, and soldered two female Dupont wires to the speaker. (These are the “innie” version of the tiny patch cables used by the Korg Volca Modular.) That lets me detach the speaker for even more compact travel setups, or swap in different speakers.

Sketch Me a Sound

The back edge of the ArduTouch has a 6-pin header you can use to load new softsynths and other Arduino sketches. You’ll need the Arduino software (a free download) and a USB-to-FTDI cable. A coworker had a generic USB-FTDI adapter, so I used another bunch of female-female Dupont wires to make my own cable. In the process, I almost burned up the adapter, because it was configured to inject power into one of the pins. Unhooking that wire fixed things, but next time I’d just buy the $6 cable from Cornfield Electronics.

After I selected the correct port in the software’s Tools menu, uploading new sketches to my ArduTouch took seconds. There are currently nine synth sketches, ranging from sound effects to drum machines. Several include arpeggiators and random melody generators. All are free downloads (scroll down the page).

My favorite is Dronetic, which triggers various evolving drones when you first touch one of the “white” keys, and then lets you solo over the top with a fuzzy lead sound. I found its low-fi quality paired well with my smoother-sounding Korg Kaossilator:

Here my ArduTouch is running the Dronetic sketch (softsynth) and Borea preset. The Kaossilator is set to a D Aeolian scale. Note that the keys on the ArduTouch don’t match the traditional notes.

The Dronetic synth is surprisingly malleable. The two red buttons call up nine different mappings for the two knobs. These range from ADSR settings for the lead voice to autowah speed for the dual drones. I compiled some performance tips here (PDF). I did notice one downside: Dronetic produced a loud whine at 6kHz, with a softer one at 12kHz. I notched them out of the video to save your ears.

Touch This Guy

Building my own instrument was satisfying, and I’m looking forward to personalizing it even more by writing my own softsynths to run on it. Altman promises, “The ArduTouch Library contains everything you need to start creating your own synthesizers. It comes with a sequence of example sketches. Read through these and try them! As well as being way-cool synthesizers, they serve as good tutorials on how to create your own synthesizer sketches for ArduTouch.” 

In fact, after wrapping up this column, I’m aiming to teach my ArduTouch to sing with the Arduino Talkie library. It’s a great time to turn off a TV and turn on a synth.

This ArduTouch is ready for its closeup.

What’s in Your Utility Belt?

The Bat Utility Belt series covers surprisingly useful synth gadgets that cost less than $100. Got a tip? Post it on FacebookInstagram, or Twitter and tag your nomination #BatUtilityBelt. You can also reach me through Batmosphere.com.

If I feature your submission in an upcoming column, you’ll win a free subscription to Synth and SoftwareOh, wait—that’s free already. Chip in!

Website: Cornfield Electronics 

Price: $29.99

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