Owner manual

-
104
-
A
m
i
crop
h
one can
b
e use
d
to
d
etect soun
d
.
H
ere yo
u
w
ill
ma
k
e a c
i
rcu
i
t t
h
at
ligh
ts t
h
e
LED
w
h
en t
he
m
i
crop
h
one
d
etects soun
d
, us
i
ng t
h
e spea
k
er as a
m
i
crop
h
one
.
Slide the switch to
p
osition B and construct th
e
circuit. When you finish the wirin
g
, by slidin
g
the
sw
i
tc
h
to pos
i
t
i
on
A
to turn on t
h
e power.
N
ow ta
lk
into the “microphone”
(
the speaker
)
or tap it lightly
;
the LED blinks.
O
bserve the schematic. I
C
1 is configured as a non
-
invertin
g
ampli
f
ier with a
g
ain o
f
about 100, and i
t
amplifies the si
g
nal from the microphone
(
the
speaker). I
C
2 is confi
g
ured as a comparator
,
comparing the output of IC1 to a reference voltag
e
from the battery. When I
C
1’s output exceeds the
re
f
erence voltage, the comparator output goes low
,
and the LED li
g
hts.
N
o
t
es:
EXPERIMENT #85: VOICE-CONTROLLED LED
S
chemati
c
Wirin
g
S
equence
:

1-2
9

2
-
30

3-110

5
-7
6
-74-
80
-7
0
-12
1

85
-
3
1-
63
-1
32

33
-
64

79-65-11
2

7
3
-
86
-
66

90
-
6
7-11
1

89
-
68
-
11
5

69
-1
09

7
5
-11
6

119-124

122
-
131