Varactor diode: used in TV tuner for tuning and channel selection.

Rectifier diode: using the unidirectional conductivity of the diode, the alternating alternating current in the direction can be transformed into pulsating DC in a single direction.

Switching diode: under the action of forward voltage, the resistance of the diode is very small and is in the on state, which is equivalent to an on switch; Under the action of reverse voltage, the resistance is large and in the cut-off state, just like an open switch. Various logic circuits can be formed by using the switching characteristics of diodes.

Detection diode: it plays the role of detection in the radio.

Amplitude limiting: after the diode is turned on in the forward direction, 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.

Freewheeling diode: it plays a freewheeling role in the inductance of switching power supply and inductive loads such as relay.

Zener diode: Zener.

Photodiode: photosensitive device.

Visible light emitting diode: emits visible light.

Damping diode: damping.

Pressure sensitive diode: pressure detection.

Gas sensing diode: gas detection.

Laser diode: CD, DVD, laser head.

Infrared diode: emits infrared rays.