How to use a multimeter to determine which pin is the base
1. Suppose we do not know whether the transistor under test is NPN or PNP type, and we cannot tell what electrode each pin is. The first step in testing is to determine which pin is the base. At this time, we pick any two electrodes (for example, these two electrodes are 1 and 2), use the two test leads of the multimeter to measure its forward and reverse resistance upside down, and observe the deflection angle of the meter needle; then, take 1 The two electrodes , 3 and the two electrodes 2 and 3 are reversed to measure their forward and reverse resistance respectively, and observe the deflection angle of the meter needle. Among these three inverted measurements, there must be two measurement results that are similar: that is, in the inverted measurement, the pointer deflection is large once and small. The remaining one must be that the pointer deflection angle is very small before and after the inverted measurement. The one that was not measured this time The pin is the base (b) we are looking for.
2. Determine the tube type After finding the base of the triode, we can determine the conductivity type of the tube based on the direction of the PN junction between the base and the other two electrodes. Touch the black test lead of the multimeter to the base, and the red test lead to any of the other two electrodes. If the deflection angle of the meter pointer is large, it means that the transistor under test is an NPN tube; if the deflection angle of the meter pointer is very small, Then the tube under test is of PNP type.
3. Determine the collector and emitter:
(1) For the NPN transistor, use the black and red test leads of the multimeter to measure the forward and reverse resistance between the two poles upside down. Although the deflection angle of the multimeter pointer is very small in the two measurements, if you observe carefully, there will always be one The deflection angle is slightly larger. At this time, the black test lead must be connected to the collector (c), and the red test lead must be connected to the emitter (e).
(2) For PNP transistors, use the black and red test leads of the multimeter to measure the forward and reverse resistance between the two poles upside down. The pointer deflection angle is slightly larger. At this time, the black test lead must be connected to the emitter ( e), the red test lead must be connected to the collector (c)
How to use a multimeter (pointer) to test the quality of a triode
