Diode Electronic Component

Learn What is Diode Electronic Component – Definition, Types, Symbol, Uses and Application of Diodes in Electronics.

Here we Learn What is Diode Electronic Component – Definition, Types, Symbol, Uses and Application of Diodes in Electronics.

What is a Diode?

A Diode is an electronic component that allows electric current to flow in one direction only. It is a semiconductor device that consists of a p-n junction.

They are most commonly used to convert AC to DC, because they pass the positive (+) part of the wave, and block the negative () part of the AC signal, or, if they are reversed, they pass only the negative part and not the positive part.

Both p-type and n-type silicon will conduct electricity just like any conductor; however, if a piece of silicon is doped p-type in one section and n-type in an adjacent section, current will flow in only one direction across the junction between the two regions.

Diodes one of the most basic semiconductor devices.

What is a Forward Biased Diode?

A diode is called forward biased if it has a positive voltage across it from from the p- to n-type material. In this condition, the diode acts rather like a good conductor, and current can flow, as in following figure:

Forward Biased Diode

There will be a small voltage across the diode, about 0.6 volts for Si, and this voltage will be largely independent of the current, very different from a resistor.

What is a Reverse Biased Diode?

If the polarity of the applied voltage is reversed, then the diode will be reverse biased and will appear non-conducting. Almost no current will flow and there will be a large voltage across the device.

Reverse Biased Diode

Types of Diodes, Symbol and Uses

Type of Diode Uses Symbol
Diode Allows flow of electric current only in one direction, from left to right
Light Emitting Diode (LED) Emits light when electric current flows
Photodiode Current flow when exposed to light
Schottky Diode Diode with low voltage drop
Tunnel Diode Diode in which electric current decreases with increase in voltage.
Varactor / Varicap Diode Diode with Variable capacitance.
Zener Diode Current flows in one direction, but also can flow in the reverse direction when above breakdown voltage.

Characteristics and Applications of Diodes

The non-symmetric behavior of diodes is due to the detailed properties of the pn-junction. The diode acts like a one-way valve for current and this is a very useful characteristic.

One application is to convert alternating current (AC), which changes polarity periodically, into direct current (DC), which always has the same polarity.

Check: How to Convert AC to DC using Diode

Normal household power is AC while batteries provide DC, and converting from AC to DC is called rectification. Diodes are used so commonly for this purpose that they are sometimes called rectifiers, although there are other types of rectifying devices.

Below figure shows the input and output current for a simple half-wave rectifier. The circuit gets its name from the fact that the output is just the positive half of the input waveform.

Half-Wave Rectifier

A full-wave rectifier circuit (Figure Below) uses four diodes arranged so that both polarities of the input waveform can be used at the output. The full-wave circuit is more efficient than the half-wave one.

Full-Wave Rectifier

How to Convert AC to DC using Diode

FAQs: What is a Diode?

A diode works based on the principle of the P-N junction. It consists of two layers of semiconductor material - one with an excess of electrons (N-type) and the other with a deficit of electrons (P-type). When a voltage is applied across the diode in the forward direction (anode positive, cathode negative), the excess electrons from the N-type layer move towards the P-type layer, allowing current to flow. In the reverse direction, the depletion region widens, preventing current flow.

There are several types of diodes, including:

  1. Rectifier Diodes: Used in power supplies to convert alternating current (AC) to direct current (DC).
  2. Light Emitting Diodes (LEDs): Emits light when current flows through it, commonly used in displays, indicators, and lighting.
  3. Zener Diodes: Designed to operate in the reverse breakdown region, used for voltage regulation and protection.
  4. Schottky Diodes: Known for their fast switching and low forward voltage drop, used in high-frequency applications.
  5. Photodiodes: Converts light into electric current, commonly used in light detection and solar cells.

Diodes serve various purposes, including:

  • Rectification: Converting AC to DC in power supplies.
  • Signal Demodulation: Extracting modulation information from radio signals.
  • Voltage Regulation: Zener diodes stabilize voltage levels.
  • Current Protection: Preventing reverse current and voltage spikes.
  • Light Emission: LEDs are used for lighting and displays.
  • Sensing: Photodiodes detect light for various applications.

The standard symbol for a diode in circuit diagrams is a triangle with a horizontal line at the tip, pointing towards a vertical line. The vertical line represents the anode (positive) terminal, and the triangle points towards the cathode (negative) terminal. This symbol indicates the one-way flow of current through the diode.

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Santosh Das

Santosh, founder of this Electronics Tutorial Website, is an Electronics Geek, Blogger and Young Entrepreneur. He possesses vast experience in the field of electronics, electronic components, PCB, Soldering, SMT, Telecommunication, ESD Safety, and PCB Assembly Tools, Equipment and Consumables. Keep visiting for daily dose of Tips and Tutorials.

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