1. Project Improvement Ideas Brian Drost Bangda Yang

2. Project Improvements Printed Circuit Board Enclosure Automatic Gain Control Increase Maximum Load Power Increase Efficiency Decrease THD Digital Audio Input Wireless Transmission

3. Printed Circuit Board Goals: – Design a PCB for your amplifier Advantages: – High probability it will work – Good experience for senior design Disadvantages: – Costs some money – Need to know how to use the CAD software

4. Printed Circuit Board Assistance – Seminar tonight on using PADS (CAD tool for PCB) Logistics – PCBs could be combined into one panel to save money – Need to finish design early so the PCB can be fabricated before the end of the term (expect 8-10 business days including shipping)

5. Enclosure Goals: – Design and build an enclosure for the amplifier & speakers Advantages: – Good experience for senior design Disadvantages: – Costs money (a lot of $ if you’re not careful) – More of a mechanical engineering project

6. Enclosure Assistance – Seminar sometime on using SolidWorks Logistics – Can be built on 3D printers – Fabrication time is around 3 days but can get busy

7. Discrete Transistor Feedback Goals: – Improve the design using feedback – Greatly improved THD (< 1%) – Precise gain (no dependence on ϐ) – Must be stable Ideas: – Talk to TAs Allowed Components: – Same as for prototype

8. Automatic Gain Control Goals: – Eliminate output dependence on input amplitude – Speaker volume does not vary with computer volume Ideas: – Need to detect signal power (multiplier) Allowed Components: – Opamps – Analog Multipliers

9. Increase Maximum Load Power Goals: – Max. load power >0.75 W per channel Ideas: – Differential output stage – Increase supply voltage Can run off power supply rather than USB

10. Increase Maximum Load Power Load power calculations: V pp P Load 1 V0.031 W 2 V0.125 W 3 V0.281 W 4 V0.5 W 5 V0.781 W 7.5 V1.758 W 10 V3.125 W

11. Differential Output Stage Goals: – Use two output stages differentially to increase output swing – Load power > 0.75 W Allowed Components: – Opamps – Power transistors

12. Increase Supply Voltage Goals: – Use a DC-DC converter to increase the supply voltage – Load power > 0.75 W Allowed Components: – Opamps & Oscillators (LM555) – Inductors – Power transistors

13. Differential Output Stage Goals: – Use two output stages differentially to increase output swing – Load power > 0.75 W Allowed Components: – Opamps – Power transistors

14. Class D Amplifier Goals: – Create a class D amplifier that meets the specs – Power > 0.5 W – Efficiency > 70% – Both channels should be able to run on USB Allowed Components: – Opamps & Oscillators (LM555) – Power transistors

15. Digital Audio Signal Goals: – Audio is transmitted digitally to the amplifier Ideas: – UART – USB (complicated) Allowed Components: – Integrated components for digital-audio conversion (microcontrollers, DACs)

16. Wireless Transmission Goals: – Receive audio wirelessly OR – Transmit audio wirelessly Ideas: – Investigate AM or FM transmission/reception Allowed Components: – Integrated components (except for radio chips)

17. Project Improvement List Printed Circuit Board Enclosure Discrete Transistor Feedback Automatic Gain Control Increase Supply Voltage Differential Output Stage Class D Amplifier Digital Audio Input Wireless Transmission

18. Other Ideas or Questions?