The Function and Recognition Method of Diode
1, the role

The main characteristic of the diode is unidirectional conductivity, that is, under the action of the forward voltage, the on-resistance is very small; and in the reverse voltage under the conduction resistance is great or infinite.

Diode by use is divided into: crystal diodes, two-way trigger diodes, high-frequency varistor diodes, varactor diodes, hair diodes, Schottky diodes.

2, identification method

Diode recognition is very simple, low-power diode N pole (negative), in the diode table is mostly used to mark a color ring, and some diodes are also marked with a diode-specific symbol "P" "N" to determine the polarity of the diode, The positive and negative poles of the LED can be identified from the length of the pin, long feet are positive, short feet are negative.

3, test notes

With a digital multimeter to support the diode, the red pen then the diode is connected to the negative pole of the diode, then the resistance is the resistance of the diode forward resistance, which is the pointer multimeter table pen connection just the opposite.

4, fault characteristics

Diode failure is mainly manifested in open circuit, short circuit and unstable voltage regulator. In these three kinds of failures, the former fault shows the power supply voltage rise; after worry about the failure of the performance of the power supply voltage becomes low to zero volts or output instability.