Elenco Electronics EP-130 - Cooking Timer

-
128
-
Wouldn’t you like to make a kitchen timer that you ca
n
use for cookin
g
meals? This circuit
g
ives out a buzze
r
s
ound for 1 to 2 seconds and automatically stops
.
Slide the switch to
p
osition B, build the circuit, and se
t
the switch to position A to turn it on.
S
et the control
to position 2 on the dial, and press the key to start th
e
timer. After about 40 seconds
,
the timer sounds for
1
to 2 seconds and stops. Use the graph you made in
p
roject 107 to preset this timer.
Look at the schematic. When the preset time is up
,
the com
p
arator
(
IC 2
)
sends out an out
p
ut. After a
time lag of 1 to 2 seconds produced by R and
C
, th
e
transistor Q1 turns on to stop the multivibrator. Th
e
s
ilicon diode discharges C and restores the circuit t
o
the original state when the timer is restarted.
No
t
es
:
EXPERIMENT #1
08
:
COO
KIN
G
TIME
R
Wiring
S
equence
:

1
-2
9

2-
30

3
-
114

5-83-70-104-116-118-137-48-26-121

27-
68

93
-
63
-2
8
-1
31

46
-
85

9
1-1
03
-
65
-4
7

9
2-
88
-
6
4-11
3

81
-
84
-
8
7-
66

67-82-8
9

69
-
9
4-117-1
38
-12
9

86
-
90
-11
5
-1
30

119
-
124

122
-
132
S
chemati
c