Briefly, the working principle of the diode

If the three major components of resistance, capacitance, and inductance are our most common electronic components, the diode is the semiconductor electronic component we see the most. Why is the diode different from the resistor, capacitor, and inductor? It is called a semiconductor electronic component. This is because the diode is made of a semiconductor material according to the characteristic that the P-pole flows to the N-pole according to its charge, so it is called a semiconductor electronic component. . Components such as transistors and MOS tubes that are more powerful than those are also semiconductor electronic components.
The diode has two pins, one is positive and the other is negative. Its maximum characteristic is unidirectional conductivity, and the charge can only flow from the positive electrode to the negative electrode. The main parameters of the diode are rated current, rated voltage, junction voltage, etc., should be selected according to actual requirements. There are many different types of diodes, such as rectifier diodes, Zener diodes, and LEDs.

The Rectifier Diode is used to convert AC to DC. In the single-phase rectifier circuit, it is divided into: a half-wave rectifier circuit using a single diode; a full-wave rectifier circuit using a transformer tap plus two diodes; A Bridge Rectifier circuit composed of four diodes. The three-phase rectifier circuit is divided into a half-wave rectifier circuit and a three-phase full-bridge rectifier circuit. The relevant knowledge of these circuits is explained in the general electronic technology textbooks. Please refer to the relevant materials for details. In our work, there are common rectifier diode applications where there are various rectifiers on the primary side of the electronic device, and the rectifier circuit in front of the vacuum AC contactor. Our common rectifier diodes are mostly black plastic 1.5A 1N4700--1N4707 series. The rectifier diode generally uses a ring of silver rings on its surface to indicate the negative electrode.
Zener diodes are commonly used in circuits that have certain DC voltage values. The Zener diode is a component fabricated by the reverse breakdown characteristic of the diode. The most important point in the circuit is that the Zener diode should be used in reverse, that is, the cathode of the Zener diode should be connected to the anode of the power supply, and the anode thereof. Connect to the negative pole of the power supply, this must be kept in mind. Commonly used Zener diodes are available in the 1N4728--1N4769 series with a regulated range of 3.3v--100v. However, since the output current of the Zener diode is not large, it is commonly used in circuits with a small operating current. Further characteristics of the voltage regulator using zener diode in which the relevant electronic circuits, it is given a limiter, a voltage on the role of the comparison.
Light-emitting diodes are components that we often touch in working instructions and everyday lighting. We generally use the English abbreviation LED to refer to it. Due to the continuous emergence of high-power LEDs, the original classification method of bright, super bright and bright is difficult to apply. The working voltage of the LED is generally about 2.5--4.5V. In the circuit above its working voltage, a suitable step-down resistor should be connected in series to ensure the normal operation of the LED. The light-emitting diode is also a polar component. Generally, the longer end of the cap LED is a positive electrode. The high-power chip-shaped LED is generally marked with a polarity symbol at the component soldering. When using or replacing note.
In addition, there are many types of diodes such as detector diodes, switching diodes, laser diodes, and varactors. You should read the parameter manual carefully when using and overhauling. In short, knowing and mastering the most basic semiconductor components such as diodes is the only way we can learn electronic knowledge.