BE Lesson 5: Make an audio oscillator

• What is a speaker?

• What is an audio oscillator?

• How do we make an audio oscillator?

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

What’s a speaker (BE demo 5-1)

+

volts

10

BE ckt 5-2. A 500 Hz tone oscillator

+

volts

120K

NPN 3904

B

C

E

PNP 3906B

C

E

+

47

10

0.1 F

Adapted from Electronic Kourseware Interactive, Discover Electronics, www.eki.com

BE ckt 5-2. Hookup diagram

+

9.0

volts

Note: Transistors face down on breadboard

47

3904

ceb

3906

ce

10

0.1 F

b

120K

Note: this circuit works equally well with a 0.1 F electrolytic capacitor.

BE demo 5-3. How BE ckt 5-2 works

BE ckt 5-4. A variable tone oscillator

+

volts

1 Meg pot

NPN 3904

B

C

E

PNP 3906B

C

E

+

47

10

0.1 F

BE ckt 5-4. Hookup diagram

+

9.0

volts

Note: Transistors face down on breadboard

47

3904

ceb

3906

ce

10

0.1 F

b

1 Meg pot

BE Lesson 5 background slides

Make a Post-it speaker

Concept published by the Pioneer Works Center for Arts and Innovation, Brooklyn, New York.www.popsci.com/paperspeaker