Transcript 5.0 Final Presentation Slides

Unplugged
A Solar Powered Audio Amplifier
With DSP Effects
Group 16
Gretchen Rivera
Hugo Castellanos
Sandra 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 Subsystem
Virtual Ground, Preamplifier, Mixer and Audio Amplifier
Audio Subsystem Overview
Power Distribution
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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
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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
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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 Subsystem
Battery, Solar Panel, Battery Charger
Power System Overview
Batteries
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,
Most expensive, circuit
light-weight, faster charge protection
times
Summary of The Current of Different Components
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
Battery Chosen
Power-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 Panels
Type
Pros
Monocrystalline
Silicon
Max efficiency 22.7%, Most expensive
produce voltage even
at low lights conditions
Polycrystalline
Silicon
Cheaper than
monocrystalline
Amorphous Silicon Least expensive, can
continue to charge at
cloudy conditions
Cons
Not able to charge when
weather is cloudy
Lowest efficiency 5-7 %,
short lifetime
Solar Panel Chosen
20 Watt Solar Panel DC 12V
Monocrystalline PV Module by HQRP
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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
R1  Vin / 2.74V 1100K
RFB3 || (RFB1 THERMISTOR || RFB2)  3.3V 14.4V  3.3V
RFB 4  250 K  RFB 3 || RFB1  THERMISTOR || RFB 2 
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 Monitoring
Subsytem
Microcontroller, DSP unit and LCD
ATmega 328
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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.
LCD
HD 44780
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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
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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 Distribution
Hugo
LCD
Charger Design
Audio Circuit
Design
Microcontroller
Coding
PCB Design
PCB Soldering
Effects Units
Enclosure
Power
Distribution
Sandra
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Gretchen
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Budget
Item
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???
Unplugged
A Solar Powered Audio Amplifier
With DSP Effects
Group 16
Gretchen Rivera
Hugo Castellanos
Sandra Munoz