User manual

4
I
n which direction is the LED connected?
The two connection wires of an LED are differently long. The longer one is the plus pole, the anode, the
s
horter one the cathode. It‘s easy to remember: The plus has one dash more than the minus and there
-
fore also makes the wire a bit lon
g
er. Most LEDs are also fl attened on the minus side, like a minus
s
i
g
n. It‘s eas
y
to remember: Cathode = short = ed
g
e.
Resistors and their colour code
s
R
esistors are used to limit current at sensitive elec
-
t
ronic components and as dropping resistors for
L
EDs. The unit of measurement for resistors is Ohm.
1
,000Ohm make one Kiloohm, in short: kOhm.
1
,000
k
O
h
m ma
k
e one Megao
h
m, in s
h
ort: MO
h
m.
T
he unit Ohm is often represented by the Omega
ch
aracter Ω
.
Th
e co
l
oure
d
rin
g
s on t
h
e resistors in
d
icate t
h
e
r
esistance. T
h
ey are muc
h
easier to recognise t
h
an
t
iny fi gures that can still be found only on very old
r
esistors. Wit
h
a
l
itt
l
e practice,
y
ou can “trans
l
ate”
t
he values from the colour codes quite quickly
.
M
ost resistors have four such colour rings. The fi rst
t
wo colour rings represent the digits, the third one is
a multi
p
lier and the fourth the tolerance. This tol-
erance ring is usually golden or silver – colours that
d
o not appear in the fi rst two rings. This makes the
reading direction clear. The tolerance value is hardly relevant in digital electronics. The table shows the
meaning of the coloured rings on resistors.
It doesn’t matter in which direction the resistor is installed. The installation direction of LEDs
,
in contrast
,
i
s
r
e
l
e
v
a
n
t.
Colou
r
Resistance in Ohm
1
. Rin
g
(tens
)
2
. Ring
(
ones)
3
. Ring
(
multiplier
)
4
. Rin
g
(
tolerance)
S
i
l
v
er
1
0
−2
=
0
,
0
1±1
0

%
Gold 10
−1
= 0,
1
±5
%
Black
0
1
0
0
=
1
Brown
1
1
1
0
1
= 1
0
±1
%
Red 2
2
1
0
2
= 1
00
±2
%
Orange 3310
3
= 1.00
0
Ye
ll
ow
4
4
1
0
4
= 1
0
.
000
G
ree
n
5
5
1
0
5
= 1
00
.
000
±
0
,5
%
Blue
6
6
1
0
6
= 1.
000
.
000
±
0
,
2
5
%
V
io
l
e
t
7
7
10
7
= 10.000.000 ±0,1%
Grey
8
8
1
0
8
= 1
00
.
000
.
000
±0
,
05%
W
h
it
e
9
9
1
0
9
= 1.
000
.
000
.
000
15007-3 Conrad Adventskalender Internet of Things 2017_en.indd 415007-3 Conrad Adventskalender Internet of Things 2017_en.indd 4 13.08.2017 17:02:5713.08.2017 17:02:57