Owner manual

-1
06
-
The electronic buzzer we built in the previous circui
t
can only make a continuous beep, but we can mak
e
a s
i
m
il
ar c
i
rcu
i
t t
h
at pro
d
uces var
i
ous s
i
ren soun
d
s
.
Your going to make a siren that gives out a soun
d
with a variable pitch. When you move the switch, thi
s
siren wails and then creates a continuous high
-
pitched noise
.
Slide the switch to position B and assemble th
e
circuit. When you complete the wirin
g
, turn the powe
r
on by slidin
g
the switch to position A. You hear the
speaker produce a sudden, roarin
g
siren sound. A
t
f
irst the sound is low and becomes higher, the
n
changes to a steady tone in about 3 to 4 seconds
.
When you press the key and release it, the capacitor
dischar
g
es and starts the siren sound a
g
ain.
You can understand how this works by looking at th
e
schematic. The pitch chan
g
es as the 10
μ
F ca
p
acito
r
is char
g
ed throu
g
h the 100k
Ω
resistor. I
C
2 is a
n
astable multivibrator. I
C
1 is a buffer between th
e
ca
p
acitor and IC 2
.
N
otes:
EXPERIMENT #
8
7:
S
WEEP
OSC
ILLAT
OR
W
iring Sequence
:
1
-2
9
2
-
30
3-116
5
-84-70-106-114-137-12
1
8
9-63-131
6
4-88-92-11
5
6
5-87-105
66
-
82
-
83
-
91
6
8-67-81
90
-
69
-
113
-
138
1
19-124
122
-
132
Schematic