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•Series Connection
Requires more voltage
The supply voltage should
be the sum of the rated
voltage required for LED
•Parallel Connection
Requires more current
The supply current should
be the sum of the rated
current requirement for LED
Each
of the seven
segment ( and the
decimal point) in a
given digit contains an
individual LED.
When
a suitable voltage
is applied to a given
segment LED, current
flows through and
illuminates that segment
LED.
Application
Numeric
display
Clocks
Calculators
Scoreboard
Infrared
is light that
has a range of
wavelengths greater
than the visible light.
Therefore, this
LED can produce
light but invisible
light.
Application
TV
remote control
transmitter
Security system
Photo
diode is a pn
junction device that
operates in reverse
bias.
The
photodiode has a
small transparent
window that allows
light to strike the pn
junction
Application
 Receiver
LED
of the infrared
This
diode maintain a
constant current
The current regulator diode
operates in forward bias and
the forward current
becomes a specified constant
value at forward voltage
ranging from about 1.5V to
about 6V
Used
primarily in highfrequency and fast
switching applications
Formed by joining a doped
semiconductor region with
metal such as gold, silver, or
platinum
 Consist
of heavily doped p and n
regions separated by an intrinsic
region
 When in reverse-bias, the pin diode
acts like a nearly constant
capacitance
 When forward-bias, it acts like a
current-controlled variable
resistance
Application



Used as a DC-controlled microwave
switch operated by rapid changes in bias
or as a modulating devise that takes
advantage of the variable forward
resistance characteristic
Used in attenuator applications because
its resistance can be controlled by the
amount of current
Used as photo detectors in fiber-optic
system
 Exhibits
a special characteristics
known as negative resistance
 This features makes it useful in
oscillator and microwave amplifier
application
 Constructed with germanium or
gallium arsenide by doping the p and
n regions much more heavily than in
a conventional rectifier diode
LASER
(Light Amplification
by Stimulated Emission of
Radiation)
LASER light is
monochromatic
Application
Pick
up system of compact disk
player
Printers and fiber communication