2

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AN49.0

April 21, 2005

FIGURE 1. Low Voltage Audio Amplifier

R5

10K

R4

10K

S1

DECREASE

S2

INCREASE

R1

220K

C1

1µF

C3

1000pF

CR1

1N4148

C2

1000pF

4

5

10

9

8

6

R3

27K

1

2

3

INC

CS

U/D

R2

27K

CR2

1N4148

J1

JACK

AUDIO INPUT

C9

1µF

3

5

6

R7

7.5K

-

+

4

6

2

3

C8

470pF

C6

.1µF

C7

.1µF

C10

10µF

LM386

2.7

R6

.1µF

C5

C4

250µF

2.7

4 OHM

SPEAKER

U2D

74HC132

74HC132

74HC132

U2B

U2A

VH

VW

VL

2

7

1

5

X9134

U1

FIGURE 2. 1 Watt Audio Amplifier

R5

10K

R4

10K

S1

DECREASE

S2

INCREASE

R1

220K

C1

1µF

C3

1000pF

CR1

1N4148

C2

1000pF

4

5

10

9

8

6

R3

27K

1

2

3

INC

CS

U/D

R2

27K

CR2

1N4148

J1

JACK

AUDIO INPUT

C9

1µF

3

5

6

R7

7.5K

-

+

7

4

2

3

C11

.1µF

C6

.1µF

C7

.1µF

LM386

2.7

R6

.1µF

C6

C4

250µF

2.7

4-16 OHM

SPEAKER

U2D

74HC132

74HC132

74HC132

U2B

U2A

VH

VW

VL

2

7

1

5

X9134

U1

6

U3

C10

10µF

OUT

IN

GND

2

1

9V-16V DC

LM78L05AC2

VR1

8

1

U2

Application Note 49