Polarity identification and quality testing of 4

If the resistance value is around 30 kn, it can still be used. If the resistance value is smaller and unstable, it indicates that the Transistors  has a large and unstable penetration current, poor thermal stability, and high noise, and should not be used. ② Test the amplification factor of AC signal current. Connect a 100 kS2 resistor between the base B and collector C, with the red probe still in contact with collector C and the black probe still in contact with emitter E. The measured resistance value should be much smaller than the resistance value measured without a 100 kN resistor connected. The smaller the value, the higher the amplification ability. For example, when the 100 kSZ resistor is not connected, the resistance value is 50 kS2. After connecting the 100 kSZ resistor, as shown in Figure 5-78 (c), the measured resistance value drops below 10 kO, indicating that this transistor has a certain amplification ability. If the resistance value drops to around 40 kn, then the amplification capability of this tube is very poor or there is no amplification capability. Transistors without amplification capability are not suitable for use. If the resistance value is unstable during the measurement process (the multimeter pointer keeps swinging), it indicates that the working stability of the Transistors  is poor, the noise is high, and the use effect is not good. If a digital multimeter is used to measure a transistor, the range should be turned to the hFE gear, and the rough mass and amplification factor of the transistor can be visually seen, as shown in Figure 5-78 (d)Transistors