How to judge the polarity of a triode with a pointer multimeter
①Base b discrimination, the pointer multimeter dial to 1K block, the black pen access to any one of the crystal transistor feet, red pen were to contact the other two feet, measure the positive and negative resistance value of the transistor, until there are two measured resistance value are very large (if the measurement of a resistance value is very large, the other resistance value of the phenomenon is very small, at this time you need to switch the black pen to an electrode again), then the black pen access to the electrode is the base of the triode b. And the tested crystal triode is PNP-type crystal triode. Measurement), the black pen access to the electrode is the base of the transistor b. And the measured crystal transistor for the PNP type crystal transistor. At this time, if the resistance value of the two electrodes are very small, then the black pen is connected to the base of the transistor b, and the measured crystal triode is an NPN type crystal triode.
② collector c and emitter e discrimination; for germanium material PNP-type and NPN-type crystal transistor, you can use the above method to determine the base of the transistor b, and then the pointer multimeter placed in the R * 1K gear, measuring the resistance of the remaining two electrodes, the two pens against the adjustment of the resistance value of the smaller measurement, if the measured transistor PNP-type, then the electrode accessed by the red pen is the collector If the measured transistor is NPN type transistor, the electrode accessed by the red pen is the emitter e, the electrode accessed by the black pen is the collector c. For NPN type silicon crystal transistor, the electrode accessed by the red pen is the emitter e, the electrode accessed by the black pen is the collector c.
For NPN-type silicon crystal transistor, the base b and collector c access to a 100KΩ resistor, according to the above measurements, in addition to the base b in addition to the measurement of the resistance between the two electrodes, where the resistance value of a smaller measurement, the black pen access to the collector of the transistor c, the electrode accessed by the red pen is the emitter e.
Know the three poles of the crystal triode, this time with a very convenient way to initially estimate the amplification capacity of the crystal triode.
For silicon material NPN-type crystal transistor; the multimeter gear dial to Rx1K position, the red pen to the collector c, the black pen to the emitter e, the base is vacated, this time a hand pinch the collector of the transistor c, the human body is equivalent to a base bias resistor, lick the base of the transistor with the tip of their tongue, at this time the pointer multimeter pointer, will be from the resistance of the case of great value! At this time, the needle of the pointer multimeter will change from a large resistance value to a very small resistance value (i.e., oscillating resistance value). This method is a little earth, but it is very applicable.
