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Switching Basics and More 89

Experiment 11: A Modular Project

R1

R2

R3

Q1

Q3

Q4

C1

D1

R4

R9

R7

Q2

C2

L1

R5

R8

R6

6V

DC

Figure 2-109. Q4 is another 2N2222 transistor that further amplifies the signal. It receives
power through R9: 2.2K.

100

K

1K

10

1

1

K

15K

0K

K

u)

00u)

K

0K

10

V

DC

Figure 2-110. This schematic is comparable

with the component layout in Figure 2-109.

Figure 2-111. The 2N2222 transistor is quite capable of driving a 3-inch loudspeaker, which
will create much better sound than a 1-inch speaker.