A First-Year Soldering and Analog Music to Light Modulator Electronics Lab Project

This paper describes an introductory electronics lab project which has been iteratively improved over three years in an introduction to engineering course. This one credit course consists of a single 100 minute lecture and lab each week during a 14 week semester and thus requires each activity to be as time efficient as possible. The project was implemented in a course that consists of both electrical and mechanical engineering students at an urban, private institution in the Midwest. For this hands-on project students learn about analog electronic components and soldering while building a circuit which can be used to make lights turn off and on with a music signal. The circuit can be connected to many music sources using an auxiliary cable and incorporates resistors, a potentiometer, an infra-red LED, an opto-TRIAC, and a TRIAC, as well as various connectors. Students spend two lab periods soldering their circuit together, making the mechanical connections to mount it in a clear plastic box and testing its performance. The students are allowed to keep their project when complete. During operation, when the music signal hits a threshold voltage Christmas lights will turn on. A successfully built circuit excites three physiologic senses (sight, hearing and touch) in that the base signal in music typically corresponds to the highest voltage which can trigger the lights. A user can hear and feel the base signal and see the lights turn on correspondingly. By analyzing a music signal during lecture, and how the various components affect this signal, students gain a practical understanding of the electronics and how they are integrated to create the circuit’s functionality. Surveys of 147 students used at the start of the semester have shown that only 37% of the students have prior experience with soldering or circuits. Of this 37%, only half still rate themselves as confident in their soldering ability at the start of class. An end of class survey and exam questions specific to this project are used to assess the quality of the project, its delivery and student learning. Results show that after completing this project 92% of students are confident in their ability to solder without supervision and 93% of students use the circuit they build for this project outside of class. The overall rating for the project is a 4.8/5 using a Likert scale making it the highest rated project ever implemented in this class. This paper describes the circuit, lab exercise, in-class curriculum and assessment of this project and provides a detailed bill of materials. Alterations to the current circuit which would provide a deeper experience with circuits and electronic components, such as amplifiers and RC filters, are also discussed and demonstrate the potential for this project to be applied in a variety of courses.