Diode

The diode is an electronics component made up of 2 junctions. In the direction passing (anode towards cathode), it lets pass the electric current. Connected in opposite direction, it blocks the current. This electronics component is used in the rectification of alternating voltages in continuous voltage, for example in the electronic assembly pont rectifying.

A diode consists of 2 pins, the anode (generally noted +) and cathode (generally noted -). It consists of two zones of silicon or polarized germanium

The electronic diagram opposite represents the assembly of test of a diode. This assembly makes it possible to measure the characteristics of a diode in direct direction (passer by). For the opposite mode, it is enough to turn over it. The characteristics tension running of a standard diode are represented in lower part. Resistance used is variable, making it possible to increase or decrease the voltage across diode.

In the direct direction, the current increases in an exponential way according to the tension (measured by the voltmeter in parallel with the diode). From the tension of threshold, the Iak current increases in a linear way according to the tension Vak (terminals of the diode).

In the opposite direction, the diode blocks the passage of the current until the maximum voltage. Then, the diode lets pass all the current. The going beyond of this maximum tension is not with the destructive one, but the diode passes in short-circuit, the current causes a thermal dissipation which finally burm it.

The characteristics above vary according to the type of diode, its power, of the room temperature,…

Various special diodes are also used: LED, ZENER, transil (transorb)

Related definitions: transistor - Thyristor - BICMOS - resistors