1. Determine which pin is the base, assuming that we don't know whether the triode under test is NPN or PNP, and we can't tell what electrode each pin is. The first step in the test is to determine which pin is the base. At this time, we randomly take 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 needle; then, take 1 , 3 two electrodes and 2, 3 two electrodes, respectively measure their forward and reverse resistance upside down, and observe the deflection angle of the hands. Among these three upside-down measurements, there must be two measurement results that are similar: that is, in the upside-down measurement, the deflection of the hands is large at one time, and the deflection is small at the other time; That pin is the base (b) we're looking for.

2. Fixed tube type After finding the base of the triode, we can determine the conductivity type of the tube according to 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 one of the other two electrodes. If the deflection angle of the pointer on the meter head is large, it means that the triode under test is an NPN tube; if the deflection angle of the pointer on the meter head is small, Then the tested tube is PNP type.

3. Определете колектора и излъчвателя: (1) For the NPN triode, 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 pointer of the multimeter is very small in the two measurements , but if you observe carefully, there will always be a deflection angle that is slightly large. 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 the PNP type triode, use the black and red pens of the multimeter to measure the forward and reverse resistance between the two poles upside down, and the pointer deflection angle is slightly larger. At this time, the black pen must be connected to the emitter ( e), the red test lead must be connected to the collector (c)