Owner manual

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139
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This experiment is a simple transistor audio amplifie
r
used as an audio si
g
nal tracer. You can use thi
s
a
m
p
lifier to troubleshoot transistor audio e
q
ui
p
ment
.
You can connect the wires to different terminals in th
e
circuit until you find the stage or component that doe
s
not pass the signal along when a circuit is not working
correctly
.
The 0.
1
μ
F input capacitor blocks DC so
y
ou ca
n
probe around circuits without worryin
g
about
d
ama
gi
n
g
t
h
e c
i
rcu
i
t.
The ampli
f
ier circuit is a common-emitter type. Th
e
trans
i
stor
s em
i
tter
i
s connecte
d
di
rect
l
y to t
h
e
i
nput
a
nd the output o
f
the earphone. Its base current is th
e
sel
f
-current type. The current
f
rom the transisto
r
collector provides current to the base
(
through th
e
470
k
Ω
resistor). This provides some stabilizin
g
negative D
C
feedback
.
You can use this ampli
f
ier to check any transisto
r
radio or ampli
f
ier you have that needs
f
ixing
.
N
o
t
es:
EXPERIMENT #117: A
U
DI
O
S
I
G
NAL H
U
NTER
Schematic
Wiring
S
equence:
4
6
-11
0
-
9
4
47-79-93-EARPH
O
N
E
1
24-48-PR
O
BE
S
1
1
9
-
80
-EARPH
O
N
E
109
-PR
O
BE
S
121
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122