Steven Engel: Engineering Portfolio
Mandolin Autopick/Arduino Table of Contents
Introduction
Background
Code
Physical Prototype
Conclusion
​
Interests Table of Contents
Main Table of Contents
Introduction
2019, Severna Park, MD
After taking Introduction to Robotics Engineering and Digital Electronics in High School, I became interested in the Arduino board and its applications. At home, I completed several small projects, coding and physically building with the Arduino to do various tasks. Some of these include playing music through a piezo speaker, detecting proximity and responding with a light with the PIR sensor, generating random place names with a suffix and prefix system and displaying them on an LCD display, lighting up a line of LEDs based on decibel level of sound input ("DJ Speakers"), as well as several other component tests and minor projects.
​
Since I am a mandolinist, my favorite project was making a mandolin autopick. This page describes the development of this project, as well as some general experience with the Arduino board.
​
Background
A mandolin is a stringed instrument, having four courses of two strings each (for eight strings total). Each course is plucked with a pick, in a back-and-forth sweeping motion. Professional mandolinists regularly employ an extremely rapid form of this motion, called tremolo. This coveted technique produces a beautiful ringing, chorus-like sound from the mandolin.
​
I could already do tremolo manually, but I decided to see if I could replicate it using the arduino.
​
First, I thought generally about the input and output of the system: through code, a user should be able to control the speed (input) at which a motor of some sort sweeps an attached pick back and forth (output). Then, I worked to build a prototype.
Code
After testing various types of motors and servos, I decided to use a servo, since servos are designed to rapidly sweep to precise positions. I taped a mandolin pick to the side of the servo and wrote code to test it, shown below.
​
The code itself is quite simple. First, the servo is set up as an output from the board and a position variable is declared and initialized to 0. Then, in an infinite loop, the servo alternates between positions '145' and '35' (based on the ideal angle of the servo, found by testing), sweeping the pick across the strings. To increase the speed of the sweeping (and produce a tremolo-like effect), the time delay between the servo position changes could be decreased.
Physical Prototype
A physical prototype was produced and tested. While the true tremolo effect is best left to human hands, the autopick was quite successful in picking the mandolin normally. In the future, the autopick could be improved by finding a better way to attach the pick to the servo, reducing the noise of the servo, and improving the speed capabilities of the servo (perhaps through an external power supply/high-power servo).
Conclusion
Through this project and many similar arduino projects, I turned engineering into a hobby and learned to have fun with it. I enjoy both the programming and physical design, as well as working with computer-based systems in general; this is part of what motivated me to pursue computer engineering.