Determination of which pin is the base
First, determine which pin is the base, assuming that we do not know whether the transistor under test is NPN-type or PNP-type, but also can not distinguish between the various pins is what electrode. The first step in the test is to determine which pin is the base. At this point, we take any two electrodes (such as the two electrodes for 1, 2), with a multimeter two pens upside down to measure its positive and negative resistance, observe the needle deflection angle; then, then take 1, 3 two electrodes and 2, 3 two electrodes, respectively, upside down to measure their positive and negative resistance, observe the needle deflection angle. In these three inverted measurements, there must be two measurements are similar: that is, inverted measurement of the needle deflection, a deflection of a small; the rest of the time is bound to be inverted before and after the measurement of the pointer deflection angle is very small, this time the unmeasured that the pin is the base of the base we are looking for (b).
Second, the tube type to find out the base of the triode, we can be based on the base and the other two electrodes between the direction of the PN junction to determine the conductive type of the tube. The black pen of the multimeter contact base, the red pen contact the other two electrodes in any electrode, if the head pointer deflection angle is very large, then the measured transistor for NPN-type tube; if the head pointer deflection angle is very small, then the measured tube that is the PNP type.
Determine the collector and emitter:
(1) For NPN-type transistor, use the black and red pens of the multimeter upside down to measure the positive and negative resistance between the two poles, although the two measurements of the multimeter pointer deflection angle is very small, but observe carefully, there will always be a deflection angle is slightly larger, this time, the black pen is connected to the collector (c), the red pen is connected to the emitter must be (e).
(2) For PNP-type transistor, the black and red pens of the multimeter inverted to measure the positive and negative resistance between the two poles, the pointer deflection angle is slightly larger once, then the black pen must be connected to the emitter (e), the red pen must be connected to the collector (c)
