Date of Award
Electrical and Computer Engineering
My senior project is an audio amplifier utilizing MOSFETs as the output transistors to drive the speaker. Within this document I cover the details of designing an amplifier, and the methods used to build it.
The most important part of the project is the output stage. In this section I chose MOSFETs over BJTs. Several advantages ensued from this decision, resulting in a simple design.
Further, the transformer must be able to supply the necessary currents for the transistors. Because large musical peaks are possible, resulting in sizable power surges, I had to obtain a large transformer with adequate specifications. It was also quite heavy.
Since it was so weighty, I had a rack-mount chassis, with the appropriate stress requirements, donated. And mounted within is the entire project, from power-on switch to circuit board to speaker terminals.
The schematic layout and simulation of the circuit was done on Workview (TM) and PSPICE respectively. These two application programs provided more than enough processing power to generate the necessary design. A printed circuit board was laid out with Autocad from the schematic and then, as explained in this paper, eventually etched.
With all this preparation and design, however, the amplifier did not work because of inadequate heat dissipation and MOSFET biasing difficulties. In the final two sections I detail what specifically went wrong, the steps needed to alleviate the above dilemmas and what I learned most about the entire project process.
Argast, Jeff, "MOSFET Audio Amplifier" (1991). Undergraduate Honors Capstone Projects. 345.
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