Transcript Unplugged - UCF EECS

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
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.
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
Specs and Requirements
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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
Overall Block Diagram
Audio Subsystem
Preamplifier, Equalization, Mixer and Audio Amplifier
Audio Subsystem Overview
Virtual Ground
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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
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
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
SSM2019 Implementation
Equalizer
• Specs called for an EQ with at least +/- 10 dB of dynamic range
• Best Solution: Baxandall Tone Control Circuit
Equalizer 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
• Design Specific Considerations
• FL=300 Hz, FH= 1kHz
• 2 Amplifiers for EQ, 2 for line level signal mixing
Baxandall Circuit
Fc=500Hz
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 12 dB at both sides of the band
Filter Frequency Response
• Frequency response with potentiometers fully CW
• Maximum Boost of 12 dB at both sides of the band
Equalizer Implementation
Problems
• Noise
• Breadboard
Capacitance
Solutions
• Use Vero board
• Use more accurate
components
Audio Amplifier IC
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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
Power Subsystem
Battery, Solar Panel, Battery Charger
Power System Overview
Solar
Panel
Battery
Charger
Voltage
Divider
LCD
Battery
9V
Regulator
Microcontroller
Audio
System
DSP
Effects
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)
BAXXBC0WT 9V
Regulator 9
130μA (1)
Miscellaneous
70mA
Total
300mA
Battery Chosen
Power-Sonic 12V/7 AH Sealed Lead Acid
(AGM) Battery
•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
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
Buck configuration
DC/DC converter
Battery Charger Prototype
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
Enclosure Considerations
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
DSP and Monitoring
Subsytem
Microcontroller, DSP unit and LCD
Arduino Mega 2560
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Preassembled with ATmega2560
256KB of flash memory
4KB EEPROM
54 digital input/output pins
16Mhz clock
5V operating voltage.
Programmable in C.
Microcontroller Block Diagram
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.
Arduino Mega2560
LCD
Nokia 3310
• 2.7-3.3V operation
2.7 to 5.5V operation
LCD drive power 3.3 to • Graphical LCD
11V
• 48 row, 85 column
Provides a choice of size output
• 40X38 mm size
240 character fonts
• Not readily available
Widely used
• Costs about $6.
Costs about $7
HD 44780
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HD 44780
• Availability
• Widely used in previous projects
• Did not need graphical functionality
• 20X4 provided enough space
• Easily interface with Arduino Mega.
HD44780
HD 44780
• Solar Panel voltage and current will be displayed
as well as battery voltage.
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.
BTSE-16FX Effects Module
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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
BTSE-16FX
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
Administrative
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
$ 10
Amplifier enclosure
Free
4ohm 15 inch speaker
Free
PCB
$ 100
Faceplate
TBD
Total Spent
$ 442
Original Budget
$ 1000
Progress
Overall (60%)
PCB (10%)
Testing (60%)
Prototyping (60%)
Parts (90%)
Design (95%)
Research (95%)
0
20
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100
Questions???
Unplugged
A Solar Powered Audio Amplifier
With DSP Effects
Group 16
Gretchen Rivera
Hugo Castellanos
Sandra Munoz