Elenco Electronics EP-130 - Buzzin with the Op Amp

-
105
-
The operational amplifier
(
op amp
)
works well as an
oscillator. In this experiment, you will build an electri
c
b
uzzer t
h
at ma
k
es a cont
i
nuous
b
eep.
B
y rotat
i
ng t
h
e
control you can change the tone of this buzzer.
When you finish the wirin
g
, set the control to the 12
o’clock position and press the key. From the speake
r
you
h
ear a cont
i
nuous
b
eep.
T
urn t
h
e contro
l
as you
press the key; the tone o
f
the buzzer changes.
The electronic buzzer only makes a beep, but it ca
n
be used
f
or many di
ff
erent purposes, as you’ll se
e
later
.
This circuit is an astable multivibrator working as a
n
oscillator to produce a square wave si
g
nal
f
or th
e
spea
k
er.
Adj
ust
i
ng t
h
e contro
l
c
h
anges t
he
f
requency, so the tone o
f
the sound is di
ff
erent. Th
e
f
requency is determined by the resistors an
d
ca
p
acitor connected to the in
p
ut terminals of the
operational ampli
f
ier. Try changing the capacitor t
o
0
.
02
μ
F or
0
.
1
μ
F and see how the tone changes
.
No
t
es
:
EXPERIMENT #
86
: B
U
ZZIN’ WITH THE
O
P AMP
Schemati
c
Wirin
g
S
equence
:

1
-2
9

2
-
30

3
-116

5
-
8
4-7
0
-1
06
-12
1

63
-27-1
38

28
-
81

6
7-90-92-11
5

91
-
68
-
105

69
-
82
-
83
-
89

1
1
9
-124

1
22-137