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Project Improvement Ideas
Brian Drost
Bangda Yang
Project Improvements
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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:
2
V pp2
Vrms

R
8R
Vpp
PLoad
1V
0.031 W
2V
0.125 W
3V
0.281 W
4V
0.5 W
5V
0.781 W
7.5 V
1.758 W
10 V
3.125 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
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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?