Owner manual

-91
-
I
n t
hi
s exper
i
ment, you w
ill
ma
k
e a m
i
crop
h
on
e
amplifier, usin
g
the operational amplifier (op amp) a
s
a non-inverting amplifier with two power sources. The
earp
h
one acts as a m
i
crop
h
one
.
Be
g
in by slidin
g
the switch to position B and finishin
g
the wirin
g
for the circuit. When your wirin
g
is ready
,
s
et t
h
e sw
i
tc
h
to pos
i
t
i
on
A
to turn on t
h
e power.
N
o
w
rotate the control
f
ully clockwise, and lightly tap you
r
“
microphone” – the earphone. The tappin
g
sound i
s
heard throu
g
h the speaker.
The earphone is a better microphone i
f
you remov
e
t
h
e en
d
t
h
at you put
i
n your ear,
b
y turn
i
ng
i
t counter
-
c
lockwise to unscrew it. To adjust the volume, turn
the control.
A
s you can o
b
serve
i
n t
h
e sc
h
emat
i
c, t
h
e operat
i
ona
l
ampli
f
ier uses two power sources: 4.5V
f
or the circui
t
and 9V for the IC. The si
g
nal from the earphone i
s
c
onnected to the operational amplifier’s non-invertin
g
input throu
g
h the control. The input is amplified, an
d
the output is applied to the trans
f
ormer. The
g
ai
n
throu
g
h the ampli
f
ier is about 100, determined by the
ratio R1/R2 (100k
Ω
k
k
/ 1k
Ω
k
= 100
)
.
No
t
es
:
EXPERIMENT #72: NON-INVERTING DUAL SUPPLY OP AM
P
W
iring Sequence:

1
-
29

2
-30

3
-
6
7-
90

2
7-
69

63
-
131

6
8-89-75

70-134

1
21-135

1
22-1
3
2

1
24-119-26-76-5-14-EARPHONE

28
-1
3
-EARPH
O
N
E
S
chematic