Elenco Electronics EP-130 - Alert Siren

-1
08
-
The sirens in Projects 88 and 89 (“
S
weep
O
scillator”
and “Fallin
g
Bomb”, respectively) adjust the pitc
h
on
l
y
i
n one
di
rect
i
on.
Thi
s c
i
rcu
i
t ma
k
es a
l
ow soun
d
that becomes higher, and goes back to its origina
l
low sound. The siren sounds only when you press
the key
.
S
et the switch to
p
osition B and build the circuit. Tur
n
on the siren by sliding the switch to position A. Whe
n
you press the key, the siren starts over at the ori
g
ina
l
low pitch. Do you hear the siren sound chan
g
e pitch
?
Does it do so as you expected? IC 1 is an oscillator
t
h
at pro
d
uces a tr
i
angu
l
ar s
i
gna
l
w
h
en you press t
h
e
ke
y
. Then the output is sent to I
C
2, which acts as a
n
astable multivibrator.
S
ee how the pitch changes when you set
C
t
o
0
.
02
μ
F and then to 0.1
μ
F.
N
o
t
es:
EXPERIMENT #
89
: ALERT
S
IRE
N
Wiring Sequence:

1-2
9

2-
30

3-116

5-7
0
-
108
-
13
7-
121

80-63-132

64-90-92-115

65-89-107

66-82-91

81-67-118

7
8
-7
9
-
68
-
11
7

69-119-124

77-
138

122-131
Schematic