Diode and transistor detection
Diode and transistor detection
In identifying and detecting common components, the resistance is the forward resistance of the diode. The smaller the positive resistance, the better. If the forward resistance is 0, it indicates the short circuit damage of the core: if the forward resistance is close to infinity.
The large value indicates the fracture of the core. Short circuit and open circuit diodes can not be used.
Reverse characteristic test
The positive pole of the multimeter red rice pen and the negative pole of the black meter pen touch diode are qualified if the foot of the meter refers to an infinite value or is close to infinity.
Digital multimeter test
Adjust the multimeter to the detector diode baffle and contact the diode's two poles with a red rice pen and a black pen (the red pen is connected to the positive pole, the black pen is connected to the negative pole), and the positive voltage drop of the DIO. You can display DE. Normal display: silicon tube 0.500 ~ 0.700 V, germanium tube 0.150 ~ 0.300 V. The voltage drop of the Schottky diode is about 0.2V, the common silicon rectifier is about 0.7V, and the light emitting diode is about 1.8V 2.3V. Switch instrument pen, monitor "1" is normal, because diode. The reverse resistance is very large, otherwise the diode will be decomposed. The positive and negative two measurements are all 0 or 1, indicating that the diode is damaged.
Recognition and detection of semiconductor triode
The full name of the transistor is semiconductor triode, also known as bipolar transistor and transistor. It is a semiconductor device using current to control the current. Its function is to amplify weak signals into electrical signals with larger amplitudes. It is also used as a non-contact switch.
Classification of triode
1 material: silicon tube and germanium tube. 2 according to the structure, NPN, PNP.
3 according to the functions: switch tube, power supply tube, Darlington tube, wide sensitive tube, etc. 4 point power supply: low power transistor, medium power tube and high power tube. 5 according to the working frequency: low frequency tube, high frequency tube and ultra high frequency tube. 6 according to the structural process: alloy tube and plane tube.
The pen 7 is mounted according to the installation mode; inserted transistor and chip transistor. The shape and graphic symbols of the common triode are shown in table 1-2-3.