1. CS-EE 481 Spring 2004 1Founder’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.)

2. CS-EE 481 Spring 2004 2Founder’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

3. CS-EE 481 Spring 2004 3Founder’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

4. CS-EE 481 Spring 2004 4Founder’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

5. CS-EE 481 Spring 2004 5Founder’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

6. CS-EE 481 Spring 2004 6Founder’s Day, 2004 University of Portland School of Engineering Define LPF

7. CS-EE 481 Spring 2004 7Founder’s Day, 2004 University of Portland School of Engineering Define HPF

8. CS-EE 481 Spring 2004 8Founder’s Day, 2004 University of Portland School of Engineering Define Current Booster IN OUT

9. CS-EE 481 Spring 2004 9Founder’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

10. CS-EE 481 Spring 2004 10Founder’s Day, 2004 University of Portland School of Engineering Results (Block Diagram) Look here

11. CS-EE 481 Spring 2004 11Founder’s Day, 2004 University of Portland School of Engineering Results (Schematic) Headphones CD Player Buffer Stage LPF HPF Current Boost

12. CS-EE 481 Spring 2004 12Founder’s Day, 2004 University of Portland School of Engineering Results (Bode Plot)

13. CS-EE 481 Spring 2004 13Founder’s Day, 2004 University of Portland School of Engineering Conclusions  Headphone Amplifier  Cheap  Versatile  Long battery life  Signal is clear  Anyone can use it

14. CS-EE 481 Spring 2004 14Founder’s Day, 2004 University of Portland School of Engineering Conclusion Continued  To change in the future  CMOS Chip  Level of the gains

15. CS-EE 481 Spring 2004 15Founder’s Day, 2004 University of Portland School of Engineering Demonstration

16. CS-EE 481 Spring 2004 16Founder’s Day, 2004 University of Portland School of Engineering Demonstration (2X)

17. CS-EE 481 Spring 2004 17Founder’s Day, 2004 University of Portland School of Engineering Demonstration (3X)

18. CS-EE 481 Spring 2004 18Founder’s Day, 2004 University of Portland School of Engineering Demonstration (4X)