A diode, also known as a crystal diode, is an electronic component that transmits current in only one direction. The circuit symbol is "VD".

A diode is a unidirectionally conductive device that has the property of flowing or not flowing current in accordance with the direction of the applied voltage. The dark black part of the general diode case represents the negative pole of the diode.

A diode is a PN junction formed by a combination of a P-type semiconductor and an N-type semiconductor, forming a space charge layer on both sides of the interface, and forming a self-built electric field.

When there is no applied voltage, the diffusion current caused by the difference in carrier concentration on both sides of the PN junction is equal to the drift current caused by the self-built electric field, and is in an electrical equilibrium state.

The so-called unidirectional conductivity means that when the current flows from the forward direction, its resistance is small, and when the current flows from the negative direction, its resistance is large, so the diode is a kind of polar component. The diode has only two legs and its outer casing is encapsulated in glass or other material.

The mark on the surface of the diode has two contents, one indicating that the element is a diode and one indicating which leg of the diode is positive and which pin is negative. Some of the markings on the surface of the diode are indicated by the letters IN or IS, indicating that the component is a diode, that is, there is a PN junction, which is a commonly used marking method in Japan and the United States. The shape of the diode is as shown.

Diode : 1N4004-TP

Zener diode

Zener diodes are polar components, and the polarity is indicated by a white horizontal bar at the end of the component. The Zener diode looks a lot like a normal axial lead diode, but the effect on the circuit is different.

Zener diode : MMSZ5245B-TP

Light-emitting diode (LED)

A light-emitting diode is a solid-state semiconductor device that converts electrical energy into visible light. It directly converts electricity into light.

The polarity of the LED is indicated by a flat edge, marked on the component body, or indicated by a notch, or by a long pin, or by a point on the component body. When inserting components, the flat side on the component body must be inserted corresponding to the flat edge indicated on the board.

Sometimes the LED board is used to mark its polarity on the board. This is done by inserting the LED on its logo. Light-emitting diodes are divided into low-power LEDs and high-power LEDs.

If you want to know more, our website has product specifications for the LEDs, you can go to Allicdata Electronics Limited to get more information.

TOPLED: LT G6SP-CBEB-25-1-Z