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Unplugged

Unplugged. Group 16 Gretchen Rivera Hugo Castellanos Sandra Munoz. A Solar Powered Audio Amplifier With DSP Effects. Project Description.

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Unplugged

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  1. Unplugged Group 16 Gretchen Rivera Hugo Castellanos Sandra Munoz A Solar Powered Audio Amplifier With DSP Effects

  2. Project Description The “unplugged” sound system is a solar powered audio amplifier that provides the freedom to play music anywhere without having to be attached to the power grid. It provides inputs for not only musical instruments, but also for microphones and an iPod or MP3 player. The “Unplugged” also provides a DSP effects unit which allows the user to choose an audio effect and a respective input to apply the effect to.

  3. Goals and Objectives • Power management system must be capable to fully charge and run off a battery. • User must be able to pick which of the effects to apply and which analog input to apply them to. • Inputs for microphone, instrument and line signal • User must be able to continuously monitor parameters such as battery voltage, solar panel voltage and current by the means of a display. • Must be portable

  4. Specs and Requirements • Should weight less than 30 pounds • Capable of delivering a minimum output of 30 Watts RMS • Capable of operating for 90 minutes • Each analog input has to be equipped with an EQ circuit with a dynamic range of +/-10 dB • To incorporate three DSP audio effects including reverb • The system must be able to run off a 12V battery • The battery must be charged solely by a 20W solar panel • The system will include 1 microphone input for low impedance microphones, one ¼ inch instrument input and an RCA input for auxiliary audio sources

  5. Overall Block Diagram

  6. Audio Subsystem Preamplifier, Equalization, Mixer and Audio Amplifier

  7. Audio Subsystem Overview

  8. Virtual Ground • TLE2426 “The Rail Splitter” from TI • Splits input voltage in half • Provides virtual ground so op-amps can be biased • Consumes only 400 µA from the 9 V LDO

  9. Testing Equipment • LM386 Audio Amplifier 4 Ohm RCA Speaker • ONLY TO TEST FUNCTIONALITY • Rigorous electrical testing will be conducted eventually • DC offset, RF Noise, Frequency Response

  10. Preamplifier IC SSM2019 from Analog Devices • 8 lead Plastic Dual-in-line-package (PDIP) • Wide range power supply: 4V-18V • Will be operating at 9V with virtual ground • Low Quiescent Current: 4.6 mA • Voltage gain of up to 3500 • Excellent noise figure @ 0.2 µV between 20 Hz – 20 kHz • ONLY ONE EXTERNAL COMPONENT

  11. SSM2019 Implementation

  12. Equalizer • Specs called for an EQ with at least +/- 10 dB of dynamic range • Best Solution: Baxandall Tone Control Circuit

  13. Equalizer IC • LME 49740 from National Semiconductor • Quad high performance, high fidelity audio operational amplifier • 14 lead DIP Package • Wide supply voltage: 4V to 17 V • Quiescent current of 20 mA for all 4 amplifiers • Excellent noise figure: 0.4 uV in the full audio range • Unity Gain Stable • Design Specific Considerations • FL=300 Hz, FH= 1kHz • 2 Amplifiers for EQ, 2 for line level signal mixing

  14. Baxandall Circuit Fc=500Hz

  15. Filter Frequency Response • Frequency response with potentiometers at the center position • Maximum deviation of 0.191 dB due to virtual ground

  16. Filter Frequency Response • Frequency Response with potentiometers fully CCW • Maximum Cut of 12 dB at both sides of the band

  17. Filter Frequency Response • Frequency response with potentiometers fully CW • Maximum Boost of 12 dB at both sides of the band

  18. Equalizer Implementation • Problems • Noise • Breadboard Capacitance Solutions • Use Vero board • Use more accurate components

  19. Audio Amplifier IC • TDA1562Q from NXP Semiconductor • 70 Watt Hybrid class H audio amplifier • 17 lead SIP Package • Operates between 8V and 14.4 Volts • Quiescent Current of 90 mA • 50 W RMS Power with 9V rail

  20. Power Subsystem Battery, Solar Panel, Battery Charger

  21. Power System Overview Battery Charger Solar Panel Battery 9V Regulator Audio System Voltage Divider DSP Effects LCD Microcontroller

  22. Batteries

  23. Summary of The Current of Different Components

  24. Battery Chosen • Valve regulated allows safe operation in any • position • Measures L: 5.95 in W: 2.56 in H: 3.70 in • High Shelf Life (% of nominal capacity at 68°F (20°C)) • 1 Month 97% • 3 Months 91% • 6 Months 83% • Weights 4.8 lbs

  25. Solar Panels

  26. Solar Panel Chosen • 20 Watt Solar Panel DC 12V Monocrystalline PV Module by HQRP • Open Circuit Voltage (Voc): 21.6V • Short Circuit Current (Isc): 1.3A • Maximum Power Voltage (Vmp): 17.2V • Maximum Power Current (Imp): 1.17A • Dimensions: 420x420x25 mm

  27. IV Curve of Solar Panel

  28. Battery Charging Circuit Buck configuration DC/DC converter

  29. Battery Charger Prototype

  30. Enclosure Considerations • Crown CE1000 • 19” X 5.25 X 12.25” • Rugged Steel • 5.3 lbs • Yamaha BR 15 Speaker • 19.1” X 25.8” X 14.4” (W,H,D) • 15 inch horn • 200W RMS • 30 lbs

  31. Enclosure Considerations • SKB 4 unit rack case • 22.50” X 9.5” X 21.50” • 12 Lbs

  32. Enclosure Concept • Amplifier enclosure mounted inside SKB case

  33. Enclosure Concept

  34. DSP and MonitoringSubsytem Microcontroller, DSP unit and LCD

  35. Arduino Mega 2560 • Preassembled with ATmega2560 • 256KB of flash memory • 4KB EEPROM • 54 digital input/output pins • 16Mhz clock • 5V operating voltage. • Programmable in C.

  36. Microcontroller Block Diagram

  37. Arduino Mega2560 • Will monitor solar panel voltage and current. • Will also monitor battery voltage. • Will interface with LCD in order to display these values • Will run a charger state machine with four states, on, off, bulk and float which will help determine what the state of the charger should be.

  38. Arduino Mega2560

  39. LCD HD 44780 • 2.7 to 5.5V operation • LCD drive power 3.3 to 11V • Provides a choice of size • 240 character fonts • Widely used • Costs about $7 Nokia 3310 • 2.7-3.3V operation • Graphical LCD • 48 row, 85 column output • 40X38 mm size • Not readily available • Costs about $6.

  40. HD 44780 • Availability • Widely used in previous projects • Did not need graphical functionality • 20X4 provided enough space • Easily interface with Arduino Mega.

  41. HD44780

  42. HD 44780 • Solar Panel voltage and current will be displayed as well as battery voltage.

  43. ADAU1702 issues • Reverb comes standard on library but chip does not support it. • The ADAU14x family supports reverb • Development board is about $400. • Would not meet budget or specs.

  44. BTSE-16FX Effects Module • Provides 16 different digital audio effects • 5V power supply • 64 X 35 mm in size • Costs about $16 dolars. • Effects will be controlled using a 4 bit grey code rotary encoder

  45. BTSE-16FX

  46. Possible Problems • PCB Design • Eagle is inadequate for our needs • 100 mm x 80 mm is too small! • Not sure how to transfer programmed ATmega to final PCB. • Heat Dissipation • Forced air- extra power consumption

  47. Administrative

  48. Budget

  49. Progress

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