What does hfe multimeter mean?
The HFE file on the multimeter is used to measure the current magnification of the transistor, and there are sockets for measuring the transistor on this meter. HFE file is mainly used to measure the amplification factor β. Before measurement, it is necessary to determine whether the triode is PNP or NPN, and at the same time determine the polarity of each pin.
Usage: when measuring, insert the triode into the corresponding polarity jack, and you can read the current amplification of the triode.
Extended data:
The meter head of the multimeter is a sensitive galvanometer. The dial on the meter head is printed with various symbols, tick 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 many scale lines printed on the dial, among which the right end marked with "Ω" is the resistance scale line, whose right end is zero and the left end is ∞, and the distribution of scale values is uneven. The symbol "-"or "DC" means DC, "~" or "AC" means AC, and "~" means the common scale line of AC and DC. A few lines of numbers under the scale line are scale values corresponding to different gears of the selector switch.
Working principle of multimeter:
The basic principle of multimeter is to use a sensitive magnetoelectric DC ammeter (microammeter) as the meter head. When a small current passes through the meter, there will be a current indication. But the meter can't pass large current, so it is necessary to shunt or step down some resistors in parallel and series on the meter to measure the current, voltage and resistance in the circuit.
What do hfe,PNP,NPN and npn on the multimeter mean?
HFE is the abbreviation of triode DC current amplification factor, which is the current amplification factor of triode; PNP and NPN represent two types of triodes.
When the triode is turned on, IE= (magnification +1)*IB has nothing to do with ICB. When ICB=0 ICB>0, there may be something wrong with the triode, so when the triode is working normally, ICB=0 regardless of whether it is working in the amplification region or the saturation region. When UEB>0.7V (silicon) (germanium 0.2V) and RC/Rb < magnification, the transistor works in the saturation region, and vice versa.
The difference between PNP triode and NPN triode is that the directions of two PN junctions are different.
PNP is a common cathode, that is, the N junction of two PN junctions is connected as the base, and the other two P junctions are the collector and emitter respectively; A triode marked with an inward arrow in the circuit diagram. NPN is the opposite.
Extended data:
The display number of digital multimeter is usually 3 1/2 to 8 1/2. There are two principles to determine the display digits of digital instruments: one is that the digits that can display all digits from 0 to 9 are integer digits;
Secondly, the numerical value of the fractional bit takes the highest digit in the maximum displayed value as the numerator, and when the full scale is used, the counted value is 2000, which indicates that the instrument has three integer digits, while the numerator of the fractional bit is 1 and the denominator is 2, so it is called 3 1/2 digits, which is pronounced as "three and a half digits", and its highest digit can only display 0 or 1(0 is usually not displayed).
3 2/3 digits (pronounced "three and two thirds digits") The highest digit of the digital multimeter can only display digits from 0 to 2, so the maximum display value is 2999. Under the same conditions, it is 50% higher than the limit of the 3 1/2 digit digital multimeter, and it is very valuable especially for measuring 380V AC voltage.
Popular digital multimeters generally belong to hand-held multimeters with 3 1/2 bit display, and 4 1/2 and 5 1/2 bit (less than 6 bits) digital multimeters are divided into hand-held and desktop types. More than 6 1/2 digits mostly belong to desktop digital multimeter.
