Types of electronic measuring instruments and their applications

　　Electronic measuring instruments can be roughly divided into the following categories according to their working principles and uses. 

　　1. Multimeter 

　　Analog voltmeter, analog multimeter (i.e. pointer multimeter VOM), digital voltmeter, digital multimeter (i.e. digital multimeter DMM) all belong to this category. This is a frequently used instrument. It can be used to measure AC/DC voltage, AC/DC current, resistance value, capacitor capacity, inductance, audio level, frequency, transistor NPN or PNP current magnification β value, etc. 

　　2. Oscilloscope 

An oscilloscope is an electronic instrument for measuring voltage waveforms. It can display the law of the measured voltage signal changing over time in a graphical way. Using an oscilloscope can not only intuitively and vividly observe the overall change of the measured physical quantity, but also measure voltage and current, compare frequency and phase, and draw characteristic curves through the waveform it displays. 

　　3. Signal generator 

　　Signal generator (including function generator) provides a signal source for repairing and debugging electronic equipment and instruments. It is an oscillator that can generate a certain waveform, frequency and amplitude. For example: generate sine wave, square wave, triangle wave, ramp wave and rectangular pulse wave, etc. 

　　4. Transistor characteristic graph 

　　The transistor characteristic graph is a special oscilloscope, which can directly observe various transistor characteristic curves and curve clusters. For example: the input, output characteristics and feedback characteristics of the three connection methods of transistor common emitter, common base and common collector; the forward and reverse characteristics of the diode; the voltage regulation or Zener characteristics of the voltage regulator; it can measure the breakdown voltage, saturation current, self or a parameter of the transistor, etc. 5. Megaohmmeter 

　　The megohmmeter (commonly known as the shaking meter) is a simple direct reading instrument for checking electrical equipment and measuring high resistance. It is usually used to measure the insulation resistance of circuits, motor windings, cables, etc. Most megohmmeters are powered by hand-cranked generators, so they are called shaking meters. Because its scale is in megohms (MΩ), it is called a megohmmeter. 


　　6. Infrared tester 

　　The infrared tester is a non-contact temperature measuring instrument, which includes an optical system and an electronic circuit. After the information is modulated and linearized, it achieves the purpose of indication, display and control. At present, there are two types of infrared thermometers in use: photon temperature measurement and thermal temperature measurement. They are mainly used in temperature measurement and control occasions such as electric furnaces, crops, railway rails, deep-buried ultra-high voltage cable joints, fire protection, gas analysis, laser reception, etc. 

　　7. Integrated circuit tester 

　　This type of instrument can test the functions and parameters of TI1, PMOS, and CMOS digital integrated circuits, and can also determine the chip model of erased characters and perform online functional tests and online status tests on integrated circuits. 

　　8. LCR parameter tester 

　　Inductance, capacitance, and resistance parameter measuring instruments can not only automatically determine the properties of components, but also display symbol graphics and display their values. It can also measure parameters such as Q, D, Z, Lp, Ls, Cp, Cs, Kp, Ks, and display equivalent circuit graphics. 

　　9. Spectrum analyzer 

　　Spectrum analyzer is widely used in frequency domain signal analysis, testing, research, and maintenance. It can simultaneously measure the amplitude and frequency of signals, test and compare multiple signals, and analyze the composition of signals. It can also test the signals of mobile phone logic and radio frequency circuits. For example: control signals and baseband signals of logic circuits, local oscillator signals, intermediate frequency signals, transmission signals of radio frequency circuits, etc. 

　　In addition to the above commonly used electronic measuring instruments, there are also time measuring instruments, bridges, phase meters, dynamic analyzers, optical measuring instruments, strain gauges, flow meters, etc.