Discrimination of the base of the triode: According to the schematic diagram of the structure of the triode, we know that the base of the triode is the common pole of the two PN junctions in the triode. Therefore, when judging the base of the triode, as long as the common pole of the two PN junctions is found, That is the base of the triode. The specific method is to adjust the multi-meter to the R×1k block of the electric block, first place the red test lead on one foot of the triode, and use the black test lead to touch the other two feet of the triode. If it is fully connected twice, the red test lead The foot placed is the base of the triode. If it is not found once, change the red test lead to the other foot of the triode and test it twice; if it is not found, change the red test lead again and test it twice. If you haven't found it yet, use the black test lead to place it on one foot of the triode, and use the red test lead to test it twice to see if it is fully connected. If it fails once, then replace it. In this way up to 12 times, the base can always be found.
Discrimination of Transistor Types: There are only two types of triodes, namely PNP type and NPN type. When judging, you only need to know whether the base is P-type or N-type. When using the multi-meter R×1k block, the black test lead represents the positive pole of the power supply. If the black test lead is connected to the base, it is turned on, indicating that the base of the transistor is P-type, and the transistor is NPN-type. If the red test lead is connected to the base, it means that the base of the triode is N-type, and the triode is PNP-type.