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A
Component
CDS
Light-emitting
diodes
C
A
C
Light-emitting diodes, or LEDs for short,
are small, sensitive components used to
signal a switch state. For example, an LED
will let you see whether a piece of
equipment is switched on or whether an
alarm has been triggered. LEDs have
terminals of two different lengths. The
shorter one is called a cathode (C), and the
longer one is an anode (A).
NTC
LEDs and other diodes have two different
poles, meaning that they only work in one
direction. When turned the wrong way,
they won't let current through and they
also won't light up.
Diodes work similarly to the model with
the water and the gate. If the current
comes from the wrong direction, the
mechanism prevents the water from
flowing through.
If the water comes from the other
direction, the gates open up and the water
flows through. That corresponds to an LED
with its poles turned the right way.
C
Illustration
A
C
Pictorial Representation
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C
A
LED2
LED1
C
A
C
B
E
C
B
T
E
7
EQUIPMENT
Schematic Symbol
LED
A
C
A
C
C
+
10 F
100 nF
R
3.3 k
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