Use a multimeter to judge the quality of transistors

Introduction: Transistors are widely used as switching tubes in circuits. When embedded programmers debug programs, they must first ensure that there are no problems with the hardware circuits before they can verify whether there are problems with the control logic of the program based on experimental results.

The following is an explanation using the PNP transistor MMBT5041 as an example

Schematic and footprint symbols

Objects on circuit board

Methods for testing the quality of PNP transistors:

Set the multimeter to the diode position, connect the black test lead to the base (BASE) of the PNP transistor, and the red test lead to the collector (COLLECTOR) and emitter (EMITTER) of the PNP transistor respectively. If the voltage drops of EB and CB are both around 0.6~0.7V, the transistor is good.

Methods for testing the quality of NPN transistors:

Set the multimeter to the diode position, connect the red test lead to the base (BASE) of the NPN transistor, and the black test lead to the collector (COLLECTOR) and emitter (EMITTER) of the NPN transistor respectively. If the voltage drops of BE and BC are both around 0.6~0.7V, the transistor is good.

The method of judging whether a MOS tube is good or bad is similar