FINAL DESIGN PROJECTTHE GEORGE WASHINGTON

UNIVERSITYSCHOOL OF ENGINEERING

AND APPLIED SCIENCEDEPARTMENT OF ELECTRICAL AND

COMPUTER ENGINEERING

By Seungryul Lee (Tommy)Professor: Zhenyu GuoTeaching Assistant: Faisal Mohd YasinMAY 3, 20001

SPECIFICATION• The power supply : 120 Vrms at 60Hz• Two channel inputs (Line and Microphone)

- Channel 2:10kohm input impedance, 25uVrms for 1Vrms output - Channel 1:47kohm input impedance, 100mVrms for 1Vrms “

• The load is a 8 Ohm speaker• Frequency response:

- Line: 20 Hz to 20kHz (with distortion < + 1 dB)- Mic : 20 Hz to 15kHz (with distortion < + 1 dB)

• Three-band graphic equalizer:- Center frequencies of 250Hz, 4kHz, and 16kHz

• One master volume control: -20 to +20 dB• One crossfader

BLOCK DIAGRAMPowerSupply Cross-fader

PowerAmplifier

(CC)

GraphicEqualizer

Load(Speaker)

AmplitudeAmplifier

(CE)

Comparators(LED)

Band-PassFilter

CIRCUIT SCHEMATIC

R4

9k

U16

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

V812Vdc

0

0

R5

500k

C9

4700u

V9

12Vdc

R73.6k

R14

14.5k

Q3

TIP32A

R2

7.5

V5

12Vdc

0

R11

0

C11

2.2n

U14

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

Q2

TIP31A

0

C7

4700u

R9

500k

0

U12

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R11

10.6k

00

C4

0.1u

R13

36k

R29

100k

C8

2.2n

U17

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

C10

0.1u

0

D1

D1N4002

D2

D1N4002

U15

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

C5

2.2n

0

U1

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2V2

FREQ = 5kVAMPL = 100mVVOFF = 0

U13

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

0

R7

1k

R28

70k

V10

12Vdc

R8

1k R13135

R22

8

0

V1

FREQ = 5kVAMPL = 100mVVOFF = 0

0

C24700u

R2

1k

V712Vdc

C1

470u

R14

10k

R12

63

R10

16k

R21

1

0

0

0

R27

100k

0 V4

12Vdc

V312Vdc

R3

8.1k

R4

8.1k

C12

2.2n

R20

1

R63.8k

0

R15

100k

0

C3

4700u

R32.65k

0

V512Vdc

C64700u

V6

12Vdc

Q1Q2N3904

R191k

R118k

V6

12Vdc

R181k

CIRCUIT SCHEMATIC (Continue)

0

DbreakD9

R25

6k

U6

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R5488

R1621k

DbreakD3

R2696k

0

U12

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

DbreakD5

V3

12Vdc

R8493

R141k

0

C3

3.3n

C4

3.3n

U5

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R6398

0R211k

R4493

R121k

R1398

R181k

R1021k

R221k

C1

3.3n

0

0

R151k

U3

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

R24

24k

C6

3.3n

R1321k

R171k

DbreakD2

DbreakD4

00

DbreakD8

R281.5k

U4

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

0

U13

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2 0

U2

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

C5

3.3n

R201k

U1

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

DbreakD6

0

V1

12Vdc

U11

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

0

R276k

R7398

0

R9488

R111k

U8

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R23

386k

V6

FREQ = 5kVAMPL = 0.1VOFF = 0

R2493

R3488

C2

3.3n

V4

12Vdc0

U9

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

DbreakD1

U7

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

DbreakD7

V212Vdc

POWER SOURCE(Voltage Regulator

V1

FREQ = 60VAMPL = 169.7VOFF = 0

D6

D1N4002 C40.1u0

V

D7

D1N4002

TX2

TX1R21

C24700u

D8

D1N4002

V

0

D5

D1N4002

C6330u

R4

500

U5LM7812C

1 2

3

IN OUT

GND

U4 LM7912C3 2

1

IN OUT

GND

R3

500

C54700u

VC3330u

0

C10.1u

CIRCUIT SCHEMATIC(Crossfader)

CIRCUIT SCHEMATIC(Cross-fader)

R5

500k

0

R63.8k

V

R2

1k

V312Vdc0

V512Vdc

0

0

VU12

LM741

3

2

74

6

1

5+

-

V+V-

OUT

OS1

OS2

R4

8.1k

U1

LM741

3

2

74

6

1

5+

-

V+V-

OUT

OS1

OS2 R9

500k

R8

1k

V1

FREQ = 5kVAMPL = 100mVVOFF = 0

0

0

0

C1

470u

0

R7

1k

0

V2

FREQ = 5kVAMPL = 100mVVOFF = 0

V4

12Vdc

V6

12Vdc 0

R3

8.1k U17

LM741

3

2

74

6

1

5+

-

V+V-

OUT

OS1

OS2

R11

CIRCUIT SCHEMATIC(Crossfader)

CIRCUIT SCHEMATIC(Common Emitter)

V5

12VdcR14

10k

0

0

R13135

0

V6

12Vdc

C24700u

R10

16k

C3

4700u

C1

470u

R12

63

Q1Q2N3904

R118k

0

CIRCUIT SCHEMATIC(Common Emitter)

• Input: 100mV, Output: 3.32V

CIRCUIT SCHEMATIC(Graphic Equalizer)

0

U13

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R18

1k

0

R5

100k

R13

36k

0

C10

2.2n

C8

2.2n

R2

70k

V712Vdc

V

V

R72.2k

C5

2.2n

0

R15

100k

C12

2.2n

V812Vdc

C4

2.2n

V101Vac0Vdc

0U14

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R4

9kR3

145k

C11

2.2n

R14

9k

0

R11

579k

U15

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2

R1

100k

U16

LM741

3

2

74

6

1

5+

-

V+

V-

OUT

OS1

OS2V

V

CIRCUIT SCHEMATICCIRCUIT SCHEMATICCIRCUIT SCHEMATICCIRCUIT SCHEMATIC(Graphic Equalizer)

Fr e que ncy

1. 0Hz 10Hz 100Hz 1. 0KHz 10KHz 100KHzV( U13: OUT) V( U14: OUT) V( U15: OUT) V( U16: OUT)

0V

2. 0V

4. 0V

6. 0V

CIRCUIT SCHEMATIC(Common Collector)

V

C9

4700u

R21

1

0

Q2

TIP31A

V11

FREQ = 5kVAMPL = 1VOFF = 0

R22

8

V10

12Vdc

0

D2

D1N4002

0

D1

D1N4002

Q3

TIP32A

R20

1 0

V9

12Vdc

0

C7

4700uC6

4700u

R181k

R191k

CIRCUIT SCHEMATIC(Common Collector)

• Input: 1V, Output: 904mV

PART LISTPART MODEL AMOUNT

Transformer 12.6V Center Tapped 1Voltage Regulator LM7812, LM7912 1 Each

Diodes D1N4002 4Op amps LM741CN 19

NPN Transistor 2N3904 1NPN Silicon

Power TransistorTIP31, TIP32 1 Each

LED Red, Yellow, Green 3 EachCapacitors 2.2n, 3.3n, 68u, 330u, 470u, 4700u… 23

Potentiometers 1k, 10k, 50k, 100k, 500k 6Resistors 1, 8, 400, 500, 1k, 8.1k, 20k… 53

Wires Various colors 10Speaker BOSE (8ohm) 1

Microphone 1Oscilloscope Tektronix TDX 460A 1

Power Supply LAMBDA 1Multimeter KEITHLEY 1CD Player Computer 1

TESTING PROCEDURE! Plug in the power supply! Turn on CD player! Volume control (Gain)! Crossfader control

- Line 1: Music- Line 2: Microphone

! Low frequency control (Bass)! Central frequency control (Voice)! High frequency control (Treble)! Plug off the power supply

PROBLEMS

• Noise: Power supply, Graphic equalizer, Common collector

• TIP31 & TIP32 are too hot because of large current

IMPROVEMENTS• Noise reduction

- Power supply: Reduce the ripple voltage(Connect capacitors between out-point of regulators and ground)

o Positive output (2V => 800mV)o Negative output (7V => 800mV)

- Graphic equalizer: Connect capacitor between 12V and ground

- Common collector: Change capacitor to smaller- Connect 7.5 ohm resistor between output of

common emitter and ground • TIP31, TIP32: Suppose to use heat sink

Questions?