Pengenalan kepada the structure of a pointer multimeter
There are many types of pointer multimeter, but the basic structure is similar. The structure of the pointer multimeter is mainly composed of three parts: the head, the changeover switch (also known as the selector switch), and the measurement line.
The head of the high sensitivity magnetoelectric mechanism, is the measurement of the display device; multimeter head is actually a sensitive ammeter. The dial on the head is printed with a variety of symbols, scale lines and numerical values. Symbol A a V a Ω that this meter is a multi-meter can measure current, voltage and resistance. The dial is printed with several scale lines, of which the right end labelled "Ω" is the resistance scale line, the right end of which is zero and the left end is ∞, and the scale values are unevenly distributed. The symbol "-" or "DC" means direct current, "~" or "AC" means alternating current. The symbol "-" or "DC" indicates direct current, "~" or "AC" indicates alternating current, and "~" indicates a scale line shared by both alternating current and direct current. Several lines of numbers under the scale line are the scale values corresponding to the different gears of the selector switch. In addition there are some symbols on the dial indicating the parameters of the meter head: such as DC 20KΩ/V, AC 9KΩ/V, etc.. There is also a mechanical zero adjustment knob (screw) on the meter head to correct the pointer at the left end to point to the zero position.
The changeover switch is used to select the type and range of the measured quantity (or multiplier): the multimeter selector switch is a multi-position rotary switch. It is used to select the measurement item and range (or multiplier). General multimeter measurement items include: "mA": DC current, "V": DC voltage, "V ~": AC voltage, "Ω ": resistance. Each measurement item is further divided into several different ranges (or multipliers) for selection.
Measuring line will be different nature and size of the measured power is converted to the meter head can accept the DC current. Figure 1 for the MF-47 type multimeter shape, the multimeter can measure DC current, DC voltage, AC voltage and resistance and other quantities of electricity. When the changeover switch is dialled to DC current, it can be connected to five contacts for DC current measurement in the ranges of 500mA, 50mA, 5mA, 0.5mA and 50μA respectively. Similarly, when the transfer switch is dialled to the ohm file, it can be used to measure the resistance with ×1, ×10, ×100, ×1KΩ, ×10KΩ multiples; when the transfer switch is dialled to the DC voltage file, it can be used to measure the DC voltage in the ranges of 0.25V, 1V, 2.5V, 10V, 50V, 250V, 500V and 1,000V; when the switch is dialled to the AC voltage file, it can be used to measure the AC voltage in the ranges of 10V, 50V, 250V, 500V and 50V; and when the switch is dialled to the AC voltage file, it can be used for 10V, 50V, 250V, 500V, 500V and 500V, 50V, 250V, 500V, 1000V range of AC voltage measurement.
