1. Rectification: The use of diode single guide, the alternating direction of alternating current into a single direction of pulse DC.

2. Switch: the diode under the action of DC voltage resistance is very small, in the on-state, equivalent to a switched on; Under the action of the reverse voltage, the resistance is large and is in the disconnected state, like an open switch. Using the switching characteristics of diodes, various logic circuits can be formed.

3. Limitation: After the diode is passed through, its forward voltage drop remains basically unchanged (0.7V for silicon tube and 0.3V for germanium tube). Using this characteristic, as a limiting element in the circuit, the signal amplitude can be limited to a certain range.

4. Continuous current: It plays a continuous current role in inductive load such as inductance and relay of switching power supply.

5. Detection: It plays a detection role in the radio.

6. Varactor diode: for TV tuner.

7. Monitor: Used on VCD, DVD, calculator and other monitors.

8. Voltage regulation: the Zener diode is essentially a surface junction silicon diode, and the Zener diode works in the reverse breakdown state. In the manufacturing process of the diode, it has a low voltage breakdown characteristic. The reverse breakdown voltage of the voltage regulator diode is constant, and a current limiting resistor is connected in series in the voltage regulator circuit, so that the current after the breakdown of the voltage regulator tube does not exceed the allowable value, so the breakdown state can last for a long time without damage.

9. Trigger: Trigger diode, also known as DIAC, is a symmetrical two-terminal semiconductor device with a three-layer structure. Commonly used to trigger bidirectional thyristors for overvoltage protection in circuits.