Discrimination of polarity and quality of transistor pins 3

③ Estimation of current amplification factor: Use a multimeter R × 100 (Q) or R × 1k (Q) to measure the resistance between the collector and emitter of a transistor (for NPN transistors, connect the black probe to the collector and the red probe to the emitter), observe the reading at this time, and then pinch the base and collector with your fingers (the two poles must not touch each other), while observing the oscillation of the pointer. The larger the swing amplitude, the higher the p-value of the tube.diode

If it is a PNP tube, swap the probes and use the above method to distinguish. Of course, nowadays tens of thousands of meters in rural areas (such as digital multimeters) have a gear endpoint (hFE) for measuring the amplification factor p. When using, first confirm the transistor type, and then insert the three pins e, b, and c of the tested transistor into the corresponding transistor plug L on the digital multimeter panel. The meter displays the approximate value of hFE.diode

The method introduced above is a relatively simple test. To further accurately test, a transistor diagram instrument can be used, which can clearly display the characteristic curve and current amplification factor of the transistor.diode

(4) Identification between germanium tube and silicon tube

To determine whether a transistor is a germanium transistor or a silicon transistor, an analog multimeter or a digital multimeter can be used. Generally, the method of measuring the emitter junction voltage is different.diode

To use an analog multimeter, the battery, resistor, and tube emitter structure need to form a circuit, and then measure the forward voltage of the emitter junction; Using a digital multimeter is more convenient as it can directly measure the forward voltage of the transmitter junction.diode