Elenco Electronics EP-130 - Double LED Blinker

-
99
-
Th
e
LED
c
i
rcu
i
ts
i
n ex
p
er
i
ments 78 an
d
7
9
(“Operational Amplifier Blinkin
g
LED” and “LE
D
F
lasher”
)
each use one LED, but the circuit in thi
s
project uses two LEDs that take turns lighting.
S
lid
e
the switch to position B and assemble the circuit.
Th
en, turn t
h
e power on
b
y s
lidi
n
g
t
h
e sw
i
tc
h
t
o
position A and wait
f
or a
f
ew seconds. The LEDs li
g
h
t
and turn o
ff
in rotation.
The operational ampli
f
ier works as an astable
multivibrator. When the output is low, LED 2 li
g
hts;
when it is hi
g
h, LED 1 li
g
hts
.
You can alter the speed o
f
the blinkin
g
by usin
g
different values for R and
C
.
S
ee how the speed of
the pulses alters when you alter the value o
f
R to
220k
Ω
k
k
.
No
t
es
:
EXPERIMENT #80: DOUBLE LED BLINKER
S
chematic
Wirin
g
S
equence:

3
1-
36
-
6
7-
90
-
9
4

33-70-135

3
4-
63
-1
3
2

93
-
68
-11
3

81
-
89
-
69

82-114-124-119

121
-
134

122
-
131