Project Improvement Ideas Brian Drost Bangda Yang

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

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

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)

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

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

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

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

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

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

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

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

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

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

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)

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)

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

Other Ideas or Questions?