June 14, 2009
June 14, 2009
June 17, 2009
14.182.1 - 14.182.7
An Audio Test Bed Design for Lab Testing and High School Recruiting Abstract
This paper presents a student-built tool that is used for audio electronics testing in the lab portion of our power electronics course. It is also sometimes used for an exhibit at our open house and high school recruiting events.
Among several other topics, our power electronics course covers the calculation of audio parameters and the design/construction of linear audio amplifiers. The instructor wanted a tool to allow direct comparison between a commercial amplifier and the amplifiers designed and built by students in the lab. Moreover, a set of good quality speakers was needed for sound level measurements. The subject of this paper, the Audio Test Bed, meets both of those requirements.
The article describes how the project got started, how the parts were acquired, and pursuant interaction with local industry donors. It then provides a technical description of what we call the Audio Test Bed, plus how it was designed and constructed by the student. Next is a discussion of the challenges encountered, how we overcame them, and lessons learned during the development and early usage of the Test Bed. Finally, we present a few ideas for possible application of the Audio Test Bed in other courses, along with some corresponding modifications.
The event that eventually led to this project was a local employer1 contacting me through one of my students. The employer was interested in starting a “mutually beneficial” relationship with us. He was willing to donate some used equipment to our program and wanted us to advertise openings he periodically had for technical help. I took a tour of his operation, learned about the business, and gained some insight into his need for part-time employees. He was especially interested in hiring a part-time technician to repair old Crown amplifiers, but also hoped to hire help for other business areas in the future as his operation expanded.
I agreed that this could be a mutually beneficial relationship. In addition to helping the local business, it would provide some experience for the students he hired. Although not design, the repair work did require learning about stereo amplifier operation in order to test, troubleshoot, repair, and in some cases upgrade the equipment. Moreover, we are a satellite campus2 and keeping our equipment and facilities up to date is always a difficult challenge. As such, even used equipment is often attractive.
Periodically, customers who sent equipment to this company for repair decided it was better to replace their old amplifier(s) with new ones rather than pay the sometimes fairly expensive repair bill. Thus, this local employer proposed donating some of these old amplifiers, along with the parts needed for repair, and letting us repair and use them. In addition to returning them to service as amplifiers, it is also straightforward to convert them into fairly high-power voltage supplies (on the order of ±80 V at several amperes of current).
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