The HFE file on the multimeter is to measure the crystal transistor current amplification, and there are sockets for measuring the crystal transistor on this kind of meter. hFE file is mainly used to measure the amplification of -value, and before the measurement, it should be determined that the transistor is PNP or NPN type, and at the same time, it should be determined that the polarity of each pin.

The multimeter head is a sensitive ammeter. The dial on the head is printed with a variety of symbols, scale lines and numerical values. The symbol A a V a Ω indicates that the meter is a multi-meter that can measure current, voltage and resistance.

The dial is printed on a number of scales, the right end of which is marked "Ω" is the resistance scale, the right end of which is zero, the left end of the ∞, the distribution of scale values is uneven. Symbol "-" or "DC" for direct current, "~" or "AC " indicates AC, and "~" indicates a scale line shared by AC and DC. Several lines of numbers under the scale line are the scale values corresponding to the different gears of the selector switch.

The basic principle of the multimeter is to use a sensitive magneto-electric DC ammeter (microammeter) as a meter head. When a small current passes through the head, a current is indicated. However, the head cannot pass large currents, so some resistors must be connected in parallel and series on the head to shunt or step down the voltage, thus measuring the current, voltage and resistance in the circuit.

Triode conduction IE = (amplification +1) * IB and ICB has no relationship, ICB = 0 ICB> 0, there may be a problem with the triode, so the triode in normal operation, regardless of whether it is working in the amplification or saturation ICB = 0. When UEB> {{0}}.7V (silicon) (germanium 0.2V), RC/RB < amplification, the triode works in the saturation area, and vice versa, work in the amplification area. In the amplification area.

The difference between a PNP-type triode and an NPN-type triode is that the direction of the two PN junctions is not the same.