Elenco Electronics EP-130 - Burglar Buzzer

-111
-
Thi
s
b
ur
gl
ar a
l
arm ma
k
es a
b
uzz
i
n
g
soun
d
w
h
en
anyone snea
ki
n
g
i
nto your
h
ouse tr
i
ps over a w
i
r
e
and breaks it off or disconnects it from a terminal. Try
to figure out how to connect a switch to the door of
your house, so that the alarm sounds when a bur
g
la
r
opens the door, instead of stretchin
g
out the wire.
Start by sliding the switch to position B an
d
assembling the circuit. When you complete th
e
wirin
g
, connect the terminals 13 and 14 to the lon
g
wire, and slide the switch to
p
osition A to turn on th
e
power. No sound comes
f
rom the speaker, at thi
s
t
i
me
.
Detach the wire
f
rom terminal 13,to test the alarm
.
Th
e spea
k
er g
i
ves out a
b
eep.
Thi
s
b
eep
i
s t
h
e a
l
ar
m
t
h
at te
ll
s you a
b
ur
gl
ar
i
s a
b
out t
h
e
b
rea
k
i
nto you
r
h
ouse
.
As you can observe in the schematic, this burgla
r
alarm uses the operational ampli
f
ier as an astabl
e
mu
l
t
i
v
ib
rator, as t
h
e e
l
ectron
i
c
b
uzzer
i
n t
h
e
l
as
t
experiment did. You can change its
f
requency b
y
using different values for the 10k
Ω
k
k
r
es
i
s
tor
a
n
d
th
e
0
.
1
μ
F ca
p
acitor. Note how the tone o
f
the buzze
r
alters when
y
ou set the 10
k
Ω r
es
i
s
tor to 47
k
Ω
or
s
w
i
tc
h
t
h
e 100
k
Ω
an
d
220
k
Ω
res
i
stors w
i
t
h
eac
h
ot
h
er
.
N
o
t
es
:
EXPERIMENT #92: BURGLAR BUZZE
R
Schemati
c
W
irin
g
Sequence:

1
-2
9

2
-
30

3
-
114

5-14-83-70-110-121

13
-
89
-
68
1
09

8
1-
63
-1
3
2

6
7-
90
-
92
-
113

69-82-84-91

119
-
124

1
22-131

1
3-14 (LONG WIRE)