Elenco Electronics EP-130 - Page 114

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114
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Now you are
g
oin
g
to produce a loud sound b
y
c
ombinin
g
an operational amplifier with tw
o
transistors. After you finish the wiring, set the switc
h
to position A to turn on the power. You hear a lou
d
sound from the speaker when you press the key.
A capacitor-resistor oscillator is the si
g
nal source fo
r
this sound. The o
p
erational am
p
lifier acts as a
n
inverting amplifier, and transistors Q2 and Q3 caus
e
the s
p
eaker to create the sound. This circuit is calle
d
a sin
g
le ended push-pull circuit (
S
EPP). You hav
e
learned about push-pull circuits. Sin
g
le ende
d
signi
f
ies that the circuit has only one output. Mos
t
ampli
f
iers have a second output that is connected t
o
the ne
g
ative (–) side of the battery.
No
t
es
:
EXPERIMENT #
95
:
O
P AMP P
O
WER AMPLIFIE
R
Wiring
S
equence
:

1
-2
9

2
-
30

3
-
90
-
6
7-
4
7-
44

5
-
9
4-4
8
-11
9
-124

7
3
-
8
1-
86
-
8
7-
3
2-11
3
-4
5
-1
3
1

33
-
63
-
43

35-46-70

7
6
-
9
2-
36
-1
3
4

9
1-
88
-1
0
4-4
0

75-
100
-
111
-
41

74-114-42

68
-
80
-
89

69
-
93

79-138

8
2-
8
4

83
-1
0
2-1
03

8
5-
99
-
101

1
12-1
3
7

1
21-135

122
-
132
S
chemati
c