BE Lesson 9Make an audio amplifier

• Use an operational amplifier (opamp) to build an audio amplifier

© 2012 C. Rightmyer, Licensed under The MIT OSI License, 20 July 2012

BE project 9-1. An audio amplifier using the LM-386 opamp

Schematic for the completed audio amplifier

Adapted from: http://www.ece.ucsb.edu/yuegroup/Teaching

Pinout for LM386N-3(U2)

1

2

3

4 5

6

7

8GAINGAIN

- INPUT

+ INPUT

GND

BYPASS

Vs

Vout

Hookup diagram for BE ckt 9-1

0.1 F

10 F

1 2 3 45678

100 F

+

0.033 F

+

470 F

placespeakerface up

10K 10

+

+1 F

9v

Stereoinput

D1 and D2 = 1N4148

D1 D2

BE project 9-2. Bonus Velleman audio amplifier kit K4001

Background slides for L9

Frequency response of an ideal audio amplifier

Http://forum.ecoustics.com/bbs/messages/34579/131062.html

A typical high-quality amplifier’s frequency response curve

Http://forum.ecoustics.com/bbs/messages/34579/131062.html

Frequency response with a lower quality amp

Http://forum.ecoustics.com/bbs/messages/34579/131062.html