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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 an iPod or any MP3 player. The “Unplugged” also provides a DSP effects unit which allows the user to choose an audio effect and apply it to a microphone or instrument.

  3. Goals and Objectives • Inputs for microphone, instrument or MP3 player • Power management system must be capable to fully charge and run off a battery. • Must be portable • User must be able to apply an audio effect to an input and monitor it by means of a display • User must be able to monitor parameters such as battery voltage, solar panel voltage and state of charge of the battery

  4. Specs and Requirements • Should weight less than 30 pounds • The system will include a ¼ inch TRS input for a microphone or instrument level signals and an 1/8 inch input for an iPod or auxiliary audio source. • Capable of delivering a minimum output of 30 Watts RMS • Capable of operating for at least 3 hours • MP3 input has to be equipped with an EQ circuit with a dynamic range of +/-6 dB • Incorporate 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

  5. Overall Block Diagram

  6. Audio Subsystem Virtual Ground, Preamplifier, Mixer and Audio Amplifier

  7. Audio Subsystem Overview

  8. Power Distribution • TLE2426 “The Rail Splitter” from TI • Splits input voltage in half • Biases IC’s properly • Consumes only 400 µA from the 9 V LDO

  9. Audio 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

  10. Pre-Amplifier • Voltage Gain of 10 • ¼ of LME49740 • High-Pass Filter at 72 Hz

  11. Mixer • ¼ LME49740

  12. Equalizer • Specs called for an EQ with at least +/- 6 dB of dynamic range • Best Solution: Baxandall Tone Control Circuit

  13. Baxandall Circuit Fl=320Hz FH=1.1kHz

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

  15. Filter Frequency Response • Frequency Response with potentiometers fully CCW • Maximum Cut of 6 dB at both sides of the band

  16. Filter Frequency Response • Frequency response with potentiometers fully CW • Maximum Boost of 6 dB at both sides of the band

  17. Audio Amplifier IC • TDA7396 from ST Microelectronics • Class H audio amplifier • 11 lead SIP Package • Operates between 8V and 14.4 Volts • Quiescent Current of 90 mA • 45 W RMS Power with 9V rail

  18. Audio Amplifier Circuit

  19. Power Subsystem Battery, Solar Panel, Battery Charger

  20. Power System Overview

  21. Batteries

  22. Summary of The Current of Different Components

  23. Battery Chosen • Valve regulated allows safe operation in any • position • Measures L:3.54in W: 2.76 in H: 3.98 in • High Shelf Life (% of nominal capacity at 68°F (20°C)) • 1 Month 97% • 3 Months 91% • 6 Months 83% • Weights 3.5lbs

  24. Solar Panels

  25. 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

  26. IV Curve of Solar Panel

  27. Battery Charging Circuit

  28. Solar Panel Mount

  29. Solar Panel Mount

  30. Enclosure • Enclosure • 19” X 5.25 X 12.25” • Aluminum • 3.3 lbs • SKB 4 unit rack case • 22.50” X 9.5” X 21.50” • 12 Lbs

  31. Enclosure Concept • Amplifier enclosure mounted inside SKB case

  32. Enclosure Concept

  33. Speaker • Gallien-Krueger 210 BLX • 16.5 x 23.5 x 16 inches(W,H,D) • 15 inch horn • 200W RMS • 30 lbs

  34. DSP and MonitoringSubsytem Microcontroller, DSP unit and LCD

  35. ATmega 328 • 32KB of flash memory • 1KB EEPROM • 23 digital input/output pins • 16Mhz clock • 5V operating voltage. • Arduino Uno as development board • Programmable in C.

  36. Microcontroller Block Diagram

  37. Atmega 328 • Monitors solar panel voltage. • Monitors battery voltage. • Runs algorithm to determine remaining battery. • Monitors audio effects unit in order to display the current audio effect. • Interfaces with LCD in order to display these values.

  38. LCD HD 44780 • 2.7 to 5.5V operation • LCD drive power 3.3 to 11V • 4 lines 20 characters each • 240 character fonts • Widely used • Costs about $7 • Easily interface with Atmel 328.

  39. HD 44780 • Solar Panel voltage and battery voltage is displayed as well as audio effect.

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

  41. BTSE-16FX

  42. Monitoring Subsystem

  43. Testing

  44. Testing • A 1kHz 2mV Pk-Pk sinusoidal wave was applied to the pre-amp and a voltage gain of 10 was confirmed • A 1kHz 1 V Pk-Pk sinusoid was applied to the audio amplifier input and a gain of 105 dB SPL was confirmed (A jackhammer 1m away is 100 dB SPL) • The solar panel was connected to the battery charger for 5 hrs charging the battery by .15V with the load disconnected • Battery discharged by .3V with load connected and solar panel attached for 5hrs.

  45. Testing (Continued) • Battery discharged by .4V with load connected with the solar panel charger turned off. • The LCD values for battery voltage and solar panel voltage were compared to multimeter measurements and they were accurate to the nearest tenth of a volt. • The grey code encoder was cycled through every possible position and the logic values were compared with a multimeter to make sure that the LCD was displaying the correct effect

  46. Administrative

  47. Timeline

  48. Work Distribution

  49. Budget

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