Outreach: The Arduinitar Project
Electronic musical instruments are a great way to introduce principles of engineering and computer science to a pre-university audience. The Arduinitar was jointly developed by Andrew McPherson and Ho Huen (QMUL electronics lab manager) with support from CS4FN (Computer Science for Fun). It is a build-it-yourself electronic guitar based on the Arduino microcontroller platform. It has been used in activities around the UK using music to teach electronic circuits and programming.
The Arduinitar is regularly featured at the TeenTech science events for teenagers. TeenTech is led by Maggie Philbin, former presenter of the "Tomorrow's World" BBC TV science programme.
Design[Click here for instructions on building your own Arduinitar!]
The Arduinitar (from "Arduino" + "guitar") is an electronic musical instrument based on the Arduino microcontroller board. The instrument consists of a set of sensors (linear and rotary potentiometers, buttons), an audio amplifier circuit with speaker, an Arduino for handling the audio synthesis, and a solderless breadboard for wiring everything together. When complete, the instrument plays like a simple guitar: moving the hand on the neck controls the pitch of the virtual strings, which are plucked using the buttons on the body.
The 8-bit microcontroller in the Arduino is just barely capable of generating real-time sampled audio. Audio synthesis is done using the Mozzi library. 16kHz sampled audio is generated using pulse width modulation, post-filtered in analog, amplified and sent to an onboard speaker. Four buttons control four virtual strings (multiple strings can sound simultaneously). The pitch of all four strings is adjusted using the linear potentiometer on the neck. Rotary potentiometers on the body control the volume and sustain time of the instrument. In its standard configuration, pitch on the neck is continuous (like a slide guitar), but a fourth control can be used to make the instrument act as if it has frets, rounding the pitch to the nearest semitone.
Many variations on the Arduinitar are possible, including bass versions with a larger speaker and lower-tuned strings, violins using a rotary encoder to measure the motion of a simple bow, and novel instruments using other sensors (light sensors, accelerometers, etc.) to control each musical parameter.
Build your own! Information on how to build an Arduinitar, including schematics, code and design files, can be found on this page.
The purpose of the Arduinitar is to introduce students to the basics of electronic circuits by having them complete the construction of the instrument. Our standard activity lasts between 30 and 45 minutes. The Arduinitar is presented as a mostly-complete instrument, but all the sensor wires have been disconnected from the Arduino. Following a discussion of what's important in a musical instrument, we discuss the difference between analog and digital systems. The students work out which controls should be analog (pitch, volume, sustain time) and which should be digital (plucking the strings) and wire up the sensors accordingly using the attached solderless breadboard. We then explore how other electronic sensors (e.g. light-dependent resistors) can be substituted to control the behaviour of the instrument.
Longer activities also explore programming by having the students modify the Arduino sketch that controls the instrument. For example, the instrument can be retuned, modified in timbre, or the strings can be made to play a predefined sequence of notes. Many creative variations are possible.
Arduinitar activities have been presented at QMUL, TeenTech and science festivals for groups ranging in age from 6 to 17 (the youngest children participating with their parents' help). We also present talks at schools and activities around the UK, often as part of a school electronics club.
The Arduinitar is regularly featured at science and technology events around the UK and at outreach events within QMUL. Recent travels with the Arduinitar include: