Engineering Students Rock

Mechanical Engineers Rock Out On Guitars They Construct Themselves

Mechanical engineers combined their skills with that of electrical engineering and   computer science to create a college class inspired by the Guitar Hero game. The hands-on course requires students to build their own guitar. To do this, students choose a shape for the guitar, which is cut out of lumber by a computer. Located under the guitar strings, magnets detect vibrations and wire coils send an electronic signal to an amplifier and speaker. Effects pedals can also distort the sound and add special effects.Skills from mechanical engineering, electrical engineering and computer science come together to form a cool kind of class that's a hit with students.

The video game Guitar Hero is a chart-busting hit. It was the inspiration that mechanical engineering graduate student and teacher Gavin Garner needed for a class assignment.

"I realized the students enjoyed pretending they were actual guitar players, and I thought, 'Why not have them actually build the real thing in the lab?'" said Garner, of the University of Virginia in Charlottesville, Va.

Garner's class isn't a music class. It's a new hands-on course combining skills from mechanical, electrical and software engineering called mechatronics. Mechanical engineering student Brad Nichols' guitar rocks.

"I was thrilled with the guitar," Nichols said. "I thought it looked great for something that was made with two by fours by students in a lab in two or three weeks. It actually sounds pretty good."

Students pick the shape and a computer automatically cuts the guitar from lumber. Basic magnets, nails and wire coils are mounted under the strings. The magnets pick up the vibrations of the strings and the wire coils send an electronic signal to an amplifier and speaker to produce sound.

"Then, the electrical signal travels down through into these effects pedals which distort the sound and add special effects, which changes the tone of the music," Garner said.

The designs show the creativity that went into the guitars, and the sound shows the science skills that created fun, useable objects that students love. "When I want to appreciate what I learned in school, I'll plug that in and strum around on it a little bit," Nichols said.

Another class assignment had students design a Mech-E-Mouse, a robot programmed to navigate through mazes to find a piece of electronic cheese.

WHAT IS PITCH: Sound waves are pressure waves. A vibrating object creates a disturbance in the surrounding air, much like a stone cast in a quiet pond will cause waves to ripple outward from the spot where the stone hit. All sound waves have wavelength and frequency. Objects that vibrate very quickly create short wavelengths and a high-pitched sound. Objects that vibrate very slowly create long wavelengths and a low-pitched sound. Frequency measures the speed of vibration in a unit called a Hertz (Hz), and 1 Hz is equivalent to 1 vibration per second. Pluck a string on a guitar, and it might vibrate 500 times per second, so the sound wave's frequency would be 500 Hertz. Pitch simply denotes those frequencies within the range of human hearing (from about 20 Hz to 20,000 Hz). The faster the rate of vibration, the higher the pitch; the slower the rate of vibration, the lower the pitch.

WHAT MAKES ELECTRIC GUITARS LOUD? Essentially this is possible because of two items: an amplifier and a pick-up. Amplifiers, as you may expect, increase the amplitude or volume of sound and other signals. For audio amplifiers that means a sound must be turned into an electric signal, and sent into the amplifier before it emerges many times louder than the level at which it was originally produced. It is essentially a speaker whose source can be a guitar, a CD, a microphone, or many other items. A pick-up transforms the movement of guitar strings into an electrical signal that can be transmitted to amplifiers or recording equipment. Some use magnets wrapped inside a coil of wire, while others use alternate methods, such as piezoelectric crystals (which respond to physical stress or deformity by creating electrical energy).

The Institute of Electrical and Electronics Engineers, Inc., contributed to the information contained in the TV portion of this report.