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									       S.A.W.
     Technologies


Low Voltage Power Amplifier

    ECE 4522 Senior Design II
         Final Presentation
           April 22, 2002
   3:00 P.M. Simrall Auditorium
 Mission Statement

S.A.W. Technologies designs and manufactures
cutting edge electronic devices to meet today’s
industrial and/or consumer needs.
                   Company Staff & Duties




  Chuck C. Shue                   Adetoro Adebiyi            Scott Wiggins
• Project Leader               • Project Member            • Project Member

• Web and Graphic Designer     • Power Supply              • Circuit board development
                                   Designer & Fabricator
• Amplifier Circuit Designer                               • Component soldering
                               • Technical Writer
• B.S.E. Finance Manager                                   • Packaging
                               • Packaging
Project Aim
A low voltage power amplifier is being designed
in order to assist manufacturers in designing
appliances with power quality problems in mind.

This amplifier can accept signals via a function
generator or even a computer’s sound card,
provided there is a software control program used
in conjunction with it.

In this way, the device can be used simply and
easily to effectively generate simulated power
quality issues for the use of whosoever finds need to.
Power Quality Problems




           Observe the light bulbs….
 The flickering/flashing action is due to various
   fluctuations and dips in the power supply.
Motivation
Currently, the electronic appliance development
industry needs a device that can simulate these
and many other types of power quality problems.




Our goal is to fulfill this need.
 Design Objectives

Highlights of major constraints:

  Output:              120 V RMS @ 10 A RMS @ 60 Hz
  Supply Efficiency:   90% or Above
  THD:                 Kept 0.1% or Below
  Package Size:        (L) 8” x (W) 8” x (H) 4”
           Design Block Diagram
 Input signal from
                       Power amplifier with
     computer                                   Electronic device
                     requisite power supplies
   soundcard or                                    to be tested
function generator
Previous design attempts
Design and Components
    Overall circuit schematic




                                                        Load




               Circuit Analysis coming up after few more slides
Design and Components
                        Input and output
                         voltage vs. time
                           (simulated)
Design and Components
                        Input and output
                         current vs. time
                           (simulated)
                    Circuit Analysis
 Supplies Source Voltage to
 Diff. Pair
                                 +90VDC Supply Rail from Rectifier.
                                            Stand by switch for the Amplifier.
 Also part of standby shut-off
 safety switch                            Differential Voltage Amplifier



         Laptop Input to AmpReality, +/- Two Mosfets Mirrored.
                   1N4148 or equiv.
                                          70 Vdc
                   Prevents differential inputone, inputsfrom exceeding 1.8V
         5Vac @ 10mA Signal               Left voltages earth (gnd).
Zener diodes (D7,D8)V pk-pk at .019mA
         Reality is 4.4 prevent           Right one, takes input signal.
over-biasing the input FETs                                                           Load

                                    Input FETs (M1, M2) nearly identically matched pair

                                 -90VDC Supply Rail from Rectifier
             Circuit Analysis

           Power up stage
        (class AB push pull)

    M5 is a bias transistor that
    sets up a voltage difference
    of ~3V between Q5 and Q4
                    Power resistors (25 @ 1 ohm,
                    each capable of 100 W
                    dissipation)
Rc = 120 ohms;
sets phase compensation                            Load
                      Reason for values:
depending on gain needed and
                      P=VI=~169V*~15A=~2500W
promotes circuit stability
                      Circuit Analysis



Feedback resistor
used in differential pair to calculate amplifier gain.
Av(out2) = ( Rf / R1 ) * ( ‘V-’ – ‘V+’)
(high values ensure low feedback current)



                     V+              V-                  Load
 Software Components
Sample soundcard interface for amplifier input
Objectives vs. Reality Summary
 Requirement           Objective              Reality

    INPUT              5VACpk-pk @      5VACpk-pk @ 0.019mA
                   10 mA @ 60Hz from     @ 60Hz from Sound
                       Sound Card              Card.

   OUTPUT         120Vac @ 10A @ 60Hz   75 Vac @ 5 A@ 60 Hz


     THD                < 0.1%                 Coming soon

  Efficiency       > 90% Supply Power          93%

     Cost              < $125.00              $330.42

     Size             8” x 8” x 4”         12” x 7 “ x 4”

Heat Sink Temp.         < 200 º F            < 200 º F
                Frequency Response
Frequency (kHz) Input (Vrms) Output (Vrms)                          Gain
     0.01           3.05         42.45                              13.92
     0.20           3.45         49.01                              14.21
     0.40           3.04         48.05                              15.81
     0.60           5.04         84.08                              16.68
     0.80           5.04         84.08                              16.69     Sample data
     1.00
     1.20
                    5.04
                    5.04
                                 84.08
                                 84.08
                                                                    16.69
                                                                    16.69
                                                                             (10Hz – 2kHz)
     1.40           5.04         84.08                              16.70
     1.60           5.04         84.09                              16.70
     1.80           5.03         84.09                              16.70
     2.00           5.03         84.09                              16.71

                             Amplifier Frequency Response

                20.00
 Gain (Vo/Vi)




                15.00
                                                                                Data plot
                10.00
                                                                             (10Hz – 10kHz)
                 5.00

                 0.00
                     0.00   2.00    4.00    6.00     8.00   10.00    12.00
                                       Frequency (kHz)
Current Problems

1. Uncommon materials needed

2. Expensive components

3. Distortion from power supply

4. Not enough space in original constraint
          Total Component Cost:
                     (Prices as ordered in bulk)
Description                                        Qtn.   Price Ea.   Price Total
AP04 Power Operational Amplifier                    1      168.6         168.6
HS06 Op. Amp. Heat Sink                             1      42.25         42.25
Professional Marchand Function Generator            1       9.99         9.99
A.C. Power Cord 25' 12/3 AWG                        1       9.99         9.99
1/8" Stereo Plug and 6' Cord                        1       2.99         2.99
Aluminum Case                                       1      19.99         19.99
Diodes 1DN4148                                      12      0.25           3
MUR 120 High Power, Fast Rectifier Diodes           2       1.25          2.5
3.25" x 3.25" Fans                                  2      10.99         21.98
Standby Switch                                      1       1.99         1.99
Wire Connector 12 AWG                               10      0.15          1.5
12 AWG Wire                                         5       0.89         4.45
18 AWG Wire                                         5       0.25         1.25
Op. Amp. Rail Power Supply Device                   1      19.99         19.99
AC-DC Power Converter for Fans                      1      12.99         12.99
14 AWG Wire 3' w/ Bannana Jacks                     3       1.99         5.97
Power Supply Terminal for Fans                      1       0.99         0.99
Total Cost:                                                             330.42

Retail Price (4 times material cost):                                  1321.68
      Cost Analysis Continued…
Original component cost objective:
          < $125.00
Actual component cost:
         $330.42
Retail price (labor + manufacture) ~ 400% of cost
           $1321.68
Reasons for high cost:
         a) original component objective didn’t take expensive high
            power components into account
         b) standard markup is 400% component cost
  Future Project Possibilities

Simulator device capable of generating higher power
Upgrades such as:
         1. Auto-Shutoff at Unsafe Temperatures
         2. Digital Temperature Gauge
         3. Smaller Packaging Size
         5. Built in function generator
   Acknowledgements
     Advisor                      Director                  Consultant




   Dr. Mark Halpin             Dr. Joseph Picone            Dr. Raymond Winton
   Associate Professor                Professor                      Professor
Mississippi State University Mississippi State University   Mississippi State University



    Not pictured:
    Sam Robinson
    Application Engineer, Apex Microtechnology

								
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