How to choose a multimeter depends on your purpose
There are many types of multimeters on the market now, and the specific multimeter you choose depends on your intended use. However, no matter which multimeter you choose, be sure not to buy the old analog multimeter. Multimeters like the MF47 are far inferior to digital multimeters in terms of measurement accuracy and functions, and the scales of some of its gears are non-linear, which brings some inconvenience to beginners in quick readings, and sometimes it is easy to misread the measurement results, so Here we only introduce the purchase of digital multimeters.
If the questioner buys a multimeter and does not use it very frequently, and only uses it at home to occasionally measure AC220V voltage or battery voltage and circuit continuity, then he can spend thirty or forty yuan to buy an ordinary 3∕½-digit digital multimeter. Ordinary digital multimeters such as DT830 and UT33D can measure AC and DC voltage, current and resistance, and are equipped with diode and buzzer settings, which are sufficient for general measurements and simple maintenance at home.
By the way, when buying this kind of multimeter, don't go for cheap. Buy those cheap digital multimeters that cost more than ten yuan. This kind of cheap digital multimeter has poor reliability and saves all the internal components that can be saved. For example, the AC voltage range of a good DT830 multimeter uses a TL062 operational amplifier connected to a precision rectifier circuit, which can accurately measure millivolt-level low-frequency AC voltage. However, those multimeters of the same model that cost more than ten yuan omit the TL062 operational amplifier and use 1N4007 diodes. Rectifier, so its AC voltage range can only measure AC voltage above 1V, and the error in measuring millivolt AC voltage is very large.
If the questioner is engaged in electrical appliance repair and needs to measure a variety of electrical parameters, it is recommended to purchase a digital multimeter with more comprehensive functions. The price of this kind of multimeter ranges from 70 to 80 yuan to hundreds of yuan. Most digital multimeters at this price range have capacitance settings, frequency settings and transistor beta settings. They can measure capacitances from 2000 to 20000μF and frequencies from 2 to 20MHz. Some digital multimeters can also measure conductance, duty cycle, temperature and inductance.
Like the VC9808+ digital multimeter, the frequency range can measure the frequency up to 20MHz, the resistance range can measure the resistance up to 2000MΩ, the temperature measurement range is -20~1000℃, and it can also measure the inductance. It can measure the inductance up to 20H. Use It is very convenient to measure various inductance coils.
Ordinary digital multimeters can only measure low-frequency sine wave AC voltages of 40 to 400 Hz. If the waveform of the measured AC voltage is a triangle wave, rectangular wave or other waveform, the measured reading error will be large. If the questioner needs to measure non-sinusoidal AC voltage, it is recommended to purchase a true RMS digital multimeter. This type of multimeter is usually marked "True RMS" on the panel and uses a true RMS measurement IC such as AD736 internally to measure AC. Voltage, it can accurately measure the AC voltage of any waveform and has nothing to do with the distortion of the waveform.
