Post on 01-Feb-2016
description
UnpluggedA Solar Powered Audio AmplifierWith DSP Effects
Group 16Gretchen RiveraHugo CastellanosSandra Munoz
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.
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
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
Overall Block Diagram
Audio SubsystemVirtual Ground, Preamplifier, Mixer and Audio Amplifier
Audio Subsystem Overview
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
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
Pre-Amplifier• Voltage Gain of 10• ¼ of LME49740• High-Pass Filter at 72 Hz
Mixer•¼ LME49740
Equalizer• Specs called for an EQ with at least +/- 6 dB of dynamic range• Best Solution: Baxandall Tone Control Circuit
Baxandall Circuit
Fl=320Hz
FH=1.1kHz
Filter Frequency Response
•Frequency response with potentiometers at the center position•Maximum deviation of 0.191 dB due to virtual ground
Filter Frequency Response
• Frequency Response with potentiometers fully CCW• Maximum Cut of 6 dB at both sides of the band
Filter Frequency Response
• Frequency response with potentiometers fully CW• Maximum Boost of 6 dB at both sides of the band
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
Audio Amplifier Circuit
Power SubsystemBattery, Solar Panel, Battery Charger
Power System Overview
Type Pros Cons
Lead-Acid Cheap price, stable at high temperatures, have multiple cycles
Low energy density, cannot be completely discharged
Nickel-Metal Hydride
Better cycle life than lead acid, creates no memory
High self-discharge 20% per month, circuit protection
Lithium-ion Highest energy density, light-weight, faster charge times
Most expensive, circuit protection
Batteries
Components Current
Virtual Ground TLE2426 400μA (1)
Preamplifier SSm2019 4.6mA (2)
LME 49740 Equalizer 20mA (1)
LME 49720 10mA (1)
Amplifier TDA1562Q 90mA (1)
LCD 300μA (1)
Microcontroller 500μA (1)
DSP Effects 100mA (1)
LM2940T 9V Regulator 7805 5V Regulator
15mA(1)8mA (1)
Miscellaneous 70mA
Total 300mA
Summary of The Current of Different Components
Battery ChosenPower-Sonic 12V/5AH Sealed Lead Acid (AGM) Battery
•Valve regulated allows safe operation in any position•Measures L: 3.54 in 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
Solar PanelsType Pros Cons
Monocrystalline Silicon
Max efficiency 22.7%, produce voltage even at low lights conditions
Most expensive
Polycrystalline Silicon
Cheaper than monocrystalline
Not able to charge when weather is cloudy
Amorphous Silicon Least expensive, can continue to charge at cloudy conditions
Lowest efficiency 5-7 %, short lifetime
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
IV Curve of Solar Panel
Battery Charging Circuit
KVVinR 100174.2/1
RFB3 || (RFB1THERMISTOR ||RFB2) 3.3V14.4V 3.3V
2||1||32504 RFBTHERMISTORRFBRFBKRFB
Solar Panel Mount
Solar Panel Mount
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
Enclosure Concept• Amplifier enclosure mounted inside SKB case
Enclosure Concept
Speaker
•Gallien-Krueger 210 BLX•16.5 x 23.5 x 16 inches(W,H,D)•15 inch horn•200W RMS• 30 lbs
DSP and MonitoringSubsytemMicrocontroller, DSP unit and LCD
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.
Microcontroller Block Diagram
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.
LCDHD 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.
HD 44780
• Solar Panel voltage and battery voltage is displayed as well as audio effect.
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
BTSE-16FX
Monitoring Subsystem
Testing
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.
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
Administrative
Timeline
Work DistributionHugo Sandra Gretchen
LCD X
Charger Design X
Audio Circuit Design
X
Microcontroller Coding
X
PCB Design X
PCB Soldering X
Effects Units X X
Enclosure X X X
Power Distribution
X
BudgetItem Price
Solar Panel $ 108.95
Arduino Mega $ 59.65
Battery $ 21.60
IC’s $ 44.63
DSP FX $ 15.00
LCD $ 7.00
Heatsinks $ 9.00
Capacitors $ 12.38
Breadboards $ 35.80
Potentiometers $ 29.53
Perforated board Free
Mis. Audio Connectors $ 40
Amplifier enclosure $40
4ohm 15 inch speaker Free
PCB $ 150
Faceplate TBD
Total Spent $ 573.54
Original Budget $ 1000
Demo • Original Enclosure
Demo (Cntd) • Original Enclosure
Questions???
UnpluggedA Solar Powered Audio AmplifierWith DSP Effects
Group 16Gretchen RiveraHugo CastellanosSandra Munoz