What does HFE represent on a multimeter
The HFE range on a multimeter measures the current amplification factor of a crystal transistor, and this type of meter has sockets for measuring crystal transistors. The hFE file is mainly used for measuring the amplification factor β Before measuring, it is necessary to determine whether the transistor is PNP or NPN type and determine the polarity of each pin.
Usage: When measuring, insert the transistor into the corresponding polarity socket to read the current amplification factor of the transistor.
Extended Information:
The head of a multimeter is a sensitive ammeter. The dial on the head is printed with various symbols, scale marks, and numerical values. The symbol A - V - Ω indicates that this meter is a multimeter that can measure current, voltage, and resistance.
There are multiple scale lines printed on the dial, with the resistance scale line marked with "Ω" at the right end, zero at the right end, and ∞ at the left end. The distribution of scale values is uneven. The symbol "-" or "DC" represents direct current, "~" or "AC" represents alternating current, and "~" represents the scale line shared by alternating current and direct current. The few lines of numbers below the scale line are the scale values corresponding to the different gear positions of the selector switch.
Working principle of a multimeter:
The basic principle of a multimeter is to use a sensitive magnetoelectric direct current meter (microampere meter) as the meter head. When a small current passes through the meter head, there will be a current indication. But the meter head cannot pass through large currents, so it is necessary to shunt or reduce voltage by connecting some resistors in parallel or series on the meter head, in order to measure the current, voltage, and resistance in the circuit.
What do hfe, PNP, NPN on a multimeter mean
HFE is the abbreviation for the DC current amplification factor of a transistor, which is the current amplification factor of the transistor; PNP and NPN represent two types of transistors.
When the transistor is on, IE=(amplification factor+1) * IB and ICB are not related. When ICB=0 and ICB>0, there may be a problem with the transistor. Therefore, when the transistor is working normally, whether it is in the amplification or saturation region, ICB=0. When UEB>0.7V (silicon) (germanium 0.2V) and RC/RB<amplification factor, the transistor operates in the saturation region, and vice versa.
The difference between PNP type transistor and NPN type transistor lies in the inconsistent direction of the two PN junctions.
PNP is a common cathode, where the N junctions of two PN junctions are connected as the base electrode, and the other two P junctions are used as collectors and emitters respectively; The circuit diagram shows a transistor with an arrow facing inward. NPN is the opposite.
