Elenco Electronics EP-130 - Slow Shut-Off Oscillator

-
86
-
You have seen how a capacitor’s char
g
e
/
dischar
ge
cycle can be used to delay certain circuit operations
.
N
ow
l
et
’
s s
l
ow t
h
e osc
ill
ator act
i
on
i
n t
hi
s pro
j
ect w
i
t
h
a
4
7
0
μ
F capacitor
.
P
ress an
d
re
l
ease t
h
e
k
ey.
Th
e c
i
rcu
i
t osc
ill
ates,
b
u
t
slowly shuts down as the capacitor char
g
es up
.
When the capacitor is fully char
g
ed, no current ca
n
f
low to the oscillator, and it is o
ff
. When
y
ou press the
key, it instantly dischar
g
es the capacitor, and the
osc
ill
ator resumes wor
ki
ng.
On its positive (+) and ne
g
ative (–) electrodes,
a
dischar
g
ed capacitor has an equal number of
electronics. Electrical charge is stored in a capacitor
by drawin
g
electrons from the positive electrode (t
o
actually make it positive
)
and addin
g
an equa
l
number of electrons to the ne
g
ative electrode (to
make it negative). Charging current or displacemen
t
current is the current that flows to char
g
e the
capacitor. The same amount o
f
current must
f
low in
the opposite direction when the capacitor i
s
di
sc
h
arg
i
ng.
Thi
s current
i
s
k
nown as
di
sc
h
arge
current or displacement current
.
With the voltmeter function if
y
ou have a V
O
M, use i
t
to measure the char
g
e on the capacitor. The
di
s
pl
acement current can
b
e measure
d
w
i
t
h
t
h
e
current
f
unction.
Thi
s e
l
ectr
i
ca
l
-storage a
bili
ty ma
k
es capac
i
tor
s
use
f
ul in many di
ff
erent ways. However, this storag
e
ability can be dangerous in very high voltage circuits
due to possible shock i
f
you are not care
f
ul with it
.
You need to dischar
g
e capacitors be
f
ore touchin
g
them i
f
they use voltages above 50V.
No
t
es
:
EXPERIMENT #
68
:
S
L
O
W
S
H
U
T-
O
FF
OSC
ILLAT
OR
Schematic
Wiring Sequence
:

1
-
29

2
-30

3
-85-105-109

4
-120

5
-
41
-
110

4
0-106-86

42
-
118
-
13
7

1
17-138-119