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A
light-emitting-diode (LED) is a semiconductor diode that emits light when an
electric current is applied in the forward direction of the device, as in the
simple LED circuit. The effect is a form of electroluminescence where incoherent
and narrow-spectrum light is emitted from the p-n junction in a solid state
material.
LEDs are widely used as indicator lights on electronic devices and increasingly
in higher power applications such as flashlights and area lighting. An LED is
usually a small area (less than 1 mm2) light source, often with optics added
directly on top of the chip to shape its radiation pattern and assist in
reflection.The color of the emitted light depends on the composition and
condition of the semi conducting material used, and can be infrared, visible, or
ultraviolet. Besides lighting, interesting applications include using UV-LEDs
for sterilization of water and disinfection of devices, and as a grow light to
enhance photosynthesis in plants.
Analog
electronic circuits are those in which signals may vary continuously with time
to correspond to the information being represented. Electronic equipment like
voltage amplifiers, power amplifiers, tuning circuits, radios, and televisions
are largely analog (with the exception of their control sections, which may be
digital, especially in modern units).
In digital
electronic circuits, electric signals take on discrete values, which are not
dependent upon time, to represent logical and numeric values. These values
represent the information that is being processed. The transistor is one of the
primary components used in discrete circuits, and combinations of these can be
used to create logic gates. These logic gates may then be used in combination to
create a desired output from an input. In this page you can find one of the
circuit.
LED Flash Turn Left and Right
(asesoris lampu rem)
Rangkaian pada gambar di bawah ini adalah berfungsi untuk
menyalakan 16 buah LED secara bergantian dari kiri ke kanan secara
bolak-balik.
Rangkaian ini terdiri dari tiga komponen utama yaitu
sumber detak (clock) yang dapat diambil dari , rangkaian pencacah pulsa
naik-turun 4 bit (IC 74LS191) serta rangkaian dekoder 4 ke 16 (IC 74LS154).
Kecepatan pergerakan nyala LED dipengaruhi oleh besarnya
frekuensi detak (clock). Setiap detak (pulsa) akan dicacah oleh IC 74LS191
dengan mode pencacahan yang dipengaruhi oleh keluaran
. Keluaran
Nand Latch akan berlogika tinggi jika pin 17 dari IC 74LS154 berlogika
rendah (kondisi ini akan membuat cacahan menaik). Demikian sebaliknya
keluaran Nand Latch akan berlogika rendah jika pin 1 dari IC 74LS154
berlogika rendah (kondisi ini akan membuat cacahan menurun).
Ketika cacahan menaik maka nyala LED akan bergerak dari
LED di pin 1 ke 17, sebaliknya maka nyala LED akan bergerak dari LED di pin
17 ke 1.

Gambar 1. Rangkaian untuk menyalakan LED bolak-balik kiri
ke kanan.

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