All about Diode Basic Electronics Lecture-3 #resistance #science #physics #electroniccomponents
Channel: Erole Technologies Homemade Engineer
Date: 2020-09-15

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Introduction:
Diode is a two terminal electronic component, these two terminals are called, anode and cathode. We can identify the cathode, by this gray mark. 
When anode is connected, to the positive terminal of power supply, and cathode is connected, to the negative terminal of power supply, then it is called forward biasing, and if we reverse the connection, then it will be called reverse biasing.
Diodes are made of semiconductor materials, like silicon or germanium.
When silicon diode is connected in forward bias, then it allows the flow of current when applied voltage across it, is over 0.7 volt. Diode restricts the flow of current in reverse biased.
There are various types of diodes, every type has a different model number, and characteristics.
For example, 1N4007, has 
turn on voltage, 0.7 volt.
maximum forward voltage, 1000 volts.
maximum reverse bias voltage, 100 volts.
maximum forward current, 1 ampere.

Diodes are widely used as rectifiers. Rectifiers are used to convert AC supply in to DC supply.
When we use a single diode with ac supply, then it blocks the negative cycle of AC current, and allow the positive cycle. This is called half wave rectifier.
When we use 4 diodes in this configuration, then it allows the positive cycle of AC current, and converts negative cycle in to positive supply. This is called full wave bridge rectifier.

L e d’s, Light emitting Diodes.
They are available in different size, packages and colors.
Every color has different turn on voltage, like, red L E D needs 1.8 volt to turn on, yellow needs 2.2 volts, green needs 3 volts, and blue l e d needs 3.6 volts.
This is the symbol of LED.
In l e d, flat side indicates the cathode, and round side indicates the anode.
L e d’s are available in two forms, colored and transparent.




IR diodes are another form of Diode, which emit infrared light. 1.5 volt is its turn on voltage. IR l e d is also called IR transmitter.
Photo diode is used, to receive the IR rays.
Photo diode turns on, when IR rays fall on it.
Photo diode is always used in reverse bias.
TV remote control system works, using IR l e d and photo diode.

Like l e d. laser is also a diode which emits light but it focuses all its light in one direction.
Laser diode turns on at 3.3 volt. this is the symbol of laser diode.