Structural Characteristics of Pointer Multimeters and Digital Multimeters
A pointer type multimeter is a multimeter that uses pointers to indicate measurement values. It is an analog display multimeter that can be used to measure resistance, DC voltage, AC voltage, DC current, transistor amplification, and decibel values.
1. The Structural Composition of a Pointer Multimeter
It usually consists of a meter head, dial, housing, pen, transfer switch, adjustment components, battery, rectifier, and resistor. The meter head generally adopts a magnetoelectric microampere DC ammeter with high internal resistance and sensitivity. It is the main component of a multimeter and consists of a pointer, magnetic circuit system, deflection system, and scale plate; The dial is printed with various symbols, scale R, and numerical values.
Before using a multimeter, it is necessary to correctly understand the meanings of various symbols and letters on the dial and the reading method of each scale.
The conversion switch is used to select the geodetic item and range. Most multimeters only have one conversion switch, while the 500 type multimeter uses two conversion switches to select the test item and range.
Use the "-" # shaped mechanical adjustment component in the center of the meter to adjust the position of the pointer when it is stationary (i.e. the pointer should be at "0" on the left side of the dial when it is stationary). The zero adjustment knob is only used when measuring the resistance of the meter.
The multimeter has two probes, one is a black probe, which is connected to the "one" end socket of the multimeter (when in the resistance range, it is connected to the positive pole of the battery inside the meter); The other is a red probe, which is connected to the "+" end of the multimeter and poked into the hole (when in the resistance range, it is connected to the negative electrode of the electric tank inside the meter, the 2500V voltage terminal socket, and the 5A current terminal socket).
2. Commonly used pointer type multimeter
The commonly used pointer type multimeter includes MF-LO type, MF-30 type, and MF-35 type. There are various types, including MF-47, MF-50, and 500.
The Structural Characteristics of Digital Multimeters
The digital multimeter adopts a liquid crystal display (LCD or LED) digital display,
A multimeter used to indicate measured values has the advantages of intuitive display and high accuracy.
1. The structural composition of a digital multimeter.
It usually consists of a display, display driver circuit, dual integral analog-to-digital (A/D) converter, AC-DC conversion circuit, conversion switch, pen, socket, power switch, various testing circuits, and protection circuits.
The display generally adopts LCD, portable digital multimeter mostly uses a three and a half digit LCD display, and desktop digital multimeter mostly uses a five and a half digit LCD display.
The display driver circuit and dual integral A/D converter usually use dedicated integrated circuits, which convert the analog signals sent by each test circuit into digital signals and directly drive the LCD to display the measured values.
