Diodes, (English: DIODE), in the electronic component, a device with two electrodes, only allows the current to flow from a single direction. Many uses are used to apply its rectification function.The Varicap Diode is used as an electron -type capacitor.Most of the current directionability of the diode is usually called "rectifying" function.The most common function of diode is that only allows the current to pass through a single direction (called the directional partial pressure), and the reverse time is blocked (called reverse bias).
Diode model
Diode positive and negative poles
Method 1: For ordinary diode, you can see the surface of the tube. One end of the white line is negative.Method 2: For the glowing diodes, the long pins are positive, short -term are negative.Method 3: If the pin is cut as long as the same, the internal metal inside the light emitting diode is very small, and the large piece is the negative electrode.Method 4: Open the multimeter, dial the knob to the pass, and connect the red and black tables to two pins.If there is a read number, one end of the red table is positive; if the reading is "1", one end of the black watch is the positive pole.
Principles of diode work
The working principle of diode (orthopedic conductivity, reverse non-conductive) crystal diode is a P-N knot formed by the P-type semiconductor and N-type semiconductor. A spatial charge layer is formed on both sides of the interface.When there is no external voltage, the diffusion current caused by the load concentration difference between the two sides of the P-N knot and the drift current caused by the self-built electric field are equal to the electrical balance.When the positive voltage bias is generated, the disappearance of the external electric field and the self -built electric field causes the spread of the carrier to increase the current.(That is, the cause of conductivity) When the reverse voltage bias is generated, the external electric field and the self -built electric field have been further strengthened to form reverse saturation currents that are not related to the reverse bias voltage value in a certain reverse voltage range.(This is the reason for non-conductivity.) Crystal diode is a P-N knot formed by a P-N-type semiconductor and N-type semiconductor. The space charge layer is formed on both sides of the interface.Due to the diffusion current caused by the load concentration difference between the P-N knots and the drifting current caused by the self-built electric field, it is in an electrical balance.When there is a positive voltage bias outside the outside world, the exterior and self -built -built electric fields interdependence effects cause the diffusion current of the carrier to increase the current.
The role of diode
1. Rectifiers use the unidirectional conductivity of the diode, which can transform the AC electricity that alternates the direction into a single direction pulse DC electricity.2. The resistance of the switch diode is very small under the actual voltage, and is in a state of diverting, which is equivalent to a connected switch. Under the influence of the reverse voltage, the resistance is large and in the deadline. Like a disconnected switch, it is like a disconnected switch.EssenceUsing the switching characteristics of the diode can form various logical circuits.

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