CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering In-Line Headphone Amplifier Authors Jim Bosak Casey Hughes Jeff Sharp Advisor Dr. Inan, Dr. Albright Industry Representative Mr. Howard Voorheis Fluke Manufacturing (Ret.)

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Agenda Introduction Jeff Sharp Background Jeff Sharp Methods Casey Hughes Results Casey Hughes Conclusions Jim Bosak Demonstration Jim Bosak

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Introduction  Team Members: Jeff Sharp, Casey Hughes, and Jim Bosak  Thanks to Dr. Aziz Inan, Mr. Howard Voorheis, Dr. Robert Albright, and Dr. Peter Osterberg  Our project amplifies output signals from personal listening devices  As a result, the sound is louder and more clear at high volumes  You will learn how we did it

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Background  Some personal listening devices lack the power  Amplification of sound  Powered by (2) 9V Batteries  Selectable Gains 2X, 3X, and 4X

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Methods  Determine what we need  Bandpass filter (20 Hz – 20 kHz)  Audible sound  Switchable Gain (2,3,4 X amplification)  Plan of action  Bandpass Filter = Buffer + LPF + HPF + Current Boost  Gain Control = Switchable feedback resistors on HPF

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Define LPF

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Define HPF

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Define Current Booster IN OUT

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Methods Cont…  Previous equations  component values  Transfer function  Bode Plots  Gain and phase margin analysis  Confirmed functionality of design

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Results (Block Diagram) Look here

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Results (Schematic) Headphones CD Player Buffer Stage LPF HPF Current Boost

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Results (Bode Plot)

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Conclusions  Headphone Amplifier  Cheap  Versatile  Long battery life  Signal is clear  Anyone can use it

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Conclusion Continued  To change in the future  CMOS Chip  Level of the gains

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Demonstration

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Demonstration (2X)

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Demonstration (3X)

CS-EE 481 Spring Founder’s Day, 2004 University of Portland School of Engineering Demonstration (4X)