Introduction to the Structure and Types of Crystal Transistors 3

Based on the high or low potential of each electrode during the operation of a transistor, the working state of the transistor can be determined. Therefore, electronic maintenance personnel often use a multimeter to measure the voltage of each pin of the transistor during maintenance, in order to determine the working condition and status of the transistor.

Using a multimeter to detect transistor

Discrimination of transistor base: According to the schematic diagram of the transistor structure, we know that the base of the transistor is the common pole of the two PN junctions in the transistor. Therefore, when discriminating the base of the transistor, we only need to find the common pole of the two PN junctions, which is the base of the transistor. The specific method is to adjust the multimeter to the resistance mode of R × 1k, first place the red probe on one pin of the transistor, and touch the other two pins of the transistor with the black probe. If both are turned on, the pin where the red probe is placed is the base of the transistor. If it cannot be found once, switch the red probe to the other pin of the transistor and test again twice; If you haven't found it yet, replace the red probe and test again twice. If it is not found yet, use a black probe to place it on one of the pins of the transistor, and use a red probe to test twice to see if it is fully connected. If it fails once, replace it. This way, at most 12 times, the base can always be found.

Discrimination of transistor types: There are only two types of transistors, PNP and NPN. When discriminating, it is only necessary to know whether the base is a P-type material or an N-type material. When using a multimeter in the R × 1k range, the black probe represents the positive pole of the power supply. If the black probe conducts when connected to the base, it indicates that the base of the transistor is made of P-type material, and the transistor is of NPN type. If the red probe is connected to the base and conducts, it indicates that the base of the transistor is made of N-type material, and the transistor is of PNP type