Discrimination of semiconductor triodes - simple judgment
Test the triode with a multimeter
(1) Turn the multimeter to the buzzer, the red pen to fix one pole. Use the black pen to test the other two poles. When there are several hundred readings respectively, the red pen is the base. Try it again and again.
(2) After the base is tested, connect the base with a red pen (B). The multimeter has a reading. The transistor is NPN.
(3) After the base is tested, connect the base with a black pen (B) and the multimeter has a reading. The transistor is PNP. The number of motherboards is only a few.