Diode Symbols – Electronic and Electrical Symbols

Electrical Technology

Diodes Symbols

Generic Diode

This symbol represents a generic diode or a rectifier diode. It is an electronic component made of semiconductor that allow current flow in one direction and block it in reverse direction.

Zener Diode

Zener diode is a type of diode that allows the flow of current in forward direction as well as reverse direction but when the reverse voltage reaches the breakdown voltage known as Zener voltage.

Schottky Diode

This type of diode made from of a small junction between an N-type semiconductor and a metal. It has no P-N junction like normal diodes. Due to which, it has very low forward voltage drop and fast switching because there is no capacitive junction (P-N junction).

Backward Diode

It is a type of diode that operates as a tunnel diode in forward bias & zener diode in reverse bias. but its tunneling effect & zener breakdown voltages are much reduced. It is used in rectification of a small voltage signal (0.1 to 0.6v).

Tunnel Diode

This type of diode is made from heavily doped P & N semiconductor that works on the principle of the tunneling effect. Tunneling is the phenomenon of escaping electrons between the PN junction due to heavy doping. Tunnel diode has a negative resistance region where the current decrease with increase in voltage & they are operated in this region.

PIN Diode

It is a three-layer diode where PIN stands for P-layer, I-layer & N-layer. The ‘I‘ intrinsic semiconductor layer is placed between heavily doped P and an N-type semiconductor. The I layer blocks high voltage in reverse bias. Due to poor reverse recovery time, they are not used in high frequency applications.

LED – Light Emitting Diode

LED (Light emitting diode) is a type of P-N junction diode that emits light when configured in forward bias. It converts electrical energy into light energy & the color of the light depends on the energy gap of the semiconductor.

LED Bi-color

It is a type of LED that has two different colors of LEDs connected in antiparallel inside single package. It can emit two different colors depending on its polarity. Changing the direction of current activates the LED with another color.

Photo Diode

A photo diode converts light energy into electrical energy. When light hits the P-N Junction it creates an electron-hole pair which flows out as electrical current. this symbol represent a photo diode.

Bi-directional Photo Diode

A generic photo diode is designed to operate in only reverse bias. This type of photo diode operates in both directions.

Common Cathode Photo Diode

This type of photo diode is made from two diodes in a single package with one common terminal i.e. cathode.

TVS Diode

Transient voltage suppression diode is a type of diode that is used for suppressing high voltage spikes. It is used for protecting circuit in reversed bias (Unidirectional TVS)

Thermal Diode

Thermal diode also known as Peltier diode is a type of diode whose thermal resistance is different in one direction than in the other direction. So it allows the heat flows in one direction leaving the other side cooler.

Laser Diode

Laser diode, just like LED it converts electrical energy into light energy. but the light produced by Laser diode produces coherent light (laser beam). It is used in optical communication, laser pointer, CD drives and laser printer etc.

Magnetically Sensitive Diode (MSD)

As the name suggests, these diodes are sensitive to magnetic field. & can be used as magnetic field sensors.

Step Recovery Diode

Step recovery diode or snap diode which instantaneously blocks the current flow when its direction is reversed. This is because of the low doping of PN junction.

Varactor / Vericap Diode

Varactor or vericap diode is a voltage controlled capacitor that has a variable PN junction capacitance. Its capacitance varies by changing the reverse voltage.

Seven Segment Display

Seven segment displays is made of 7 LEDs in specific pattern. It is used for displaying decimal numerals and English alphabets. However it can be designed to display numerous characters.

5×7 LED dot Matrix Display

It is made of LEDs in 5×7 matrix pattern that is why it is known as dot matrix display. It has 5 columns and 7 rows of dot shaped LEDs next to each other. It is used for displaying characters & shapes in digital devices.

Silicon Controlled Rectifier (SCR)

SCR or thyristor is a diode made from PNPN junction. SCR is activated (to conduct current) if the forward voltage increases its forward breakdown voltage or through a positive gate pulse

Shockley Diode

It is a PNPN diode just like SCR but it does not have any gate control input. it is only triggered by applying forward voltage higher than its breakdown voltage.

Bridge Rectifier

It is also known as full wave rectifier. It is made up of four diodes that converts the AC signal into DC signal. the process of conversion from AC to DC is known as Rectification.

Variable Bridge Rectifier

This type of bridge rectifier is made up of SCR (thyristors). The thyristors switching time can be controlled by its gate input. thus this rectifier output can vary by controlling its gate input.

Three Phase Rectifier

A three phase rectifier converts the three phase electrical signal into a DC rectified output. it is a modified form a full wave bridge rectifier where 2 pair of diodes converts each phase.

Related Electronic and Electrical Symbols: