How to buy a Multimeter depends on how you want to use it.
There are many types of multimeters on the market nowadays, and the specific type of multimeter to choose depends on your own use. However, regardless of which type of multimeter, the old pointer multimeter must not buy. Like MF47 this kind of multimeter regardless of the measurement accuracy or function is far less than the digital multimeter, and some of its gear scale is non-linear, which brings some inconvenience to the beginner's fast readings, and sometimes it is also easy to read the results of the wrong measurements, it is only here to introduce the purchase of digital multimeter.
Ordinary 3∕½ digit digital multimeter.
If the questioner to buy a multimeter use frequency is not high, placed in the home is only occasionally used to measure the AC220V voltage or battery voltage and line on and off, then spend thirty or forty yuan to buy a common 3∕½ digital multimeter can be. Like DT830, UT33D such ordinary digital multimeter can measure AC and DC voltage, current and resistance, and with diode and buzzer gear, enough to meet the general measurement and simple maintenance at home.
By the way, when buying this kind of multimeter, do not try to cheap, buy those more than ten dollars of digital multimeter, the reliability of this cheap is relatively poor, the internal can save the components are saved. Like a good DT830 multimeter AC voltage file is connected to a precision rectifier circuit using the TL062 op-amp, can accurately measure the millivolt level of low-frequency AC voltage, while the same type of multimeter with more than ten dollars inside the omission of the TL062 op-amp, the use of 1N4007 diode rectifier, the AC voltage file can only be measured more than 1V AC voltage, measured in millivolts, AC voltage error is very large.
Multi-function digital multimeter.
If the questioner is engaged in electrical repair, the need to measure a variety of electrical parameters, it is recommended to buy a full-featured digital multimeter. These multimeters are available at prices ranging from seventy to eighty to hundreds of dollars. Most of the digital multimeter at this price with capacitance file, frequency file and transistor β file, they can measure the capacitance of 2000 ~ 20000μF, 2 ~ 20MHz frequency. Some digital multimeter can also measure conductivity, duty cycle, temperature and inductance.
Like the GD128 digital multimeter, the frequency file can measure up to 20MHz frequency, resistance file can measure up to 2000MΩ resistance, temperature measurement range of -20~1000 ℃, and can also measure inductance, its maximum can measure 20H inductance, used to measure a variety of inductive coils is very convenient.
True RMS digital multimeter.
Ordinary digital multimeter can only measure 40~400Hz low frequency sinusoidal AC voltage, if the measured AC voltage waveform is triangular wave, rectangular wave or other waveforms, this time the measured reading error is very large. If the questioner needs to measure non-sinusoidal AC voltage, it is recommended to buy a true RMS digital multimeter, this multimeter is generally marked on the panel "True RMS", the internal use of AD736 such as true RMS measurement IC to measure the AC voltage, you can accurately measure the AC voltage of any waveform, and with the waveform It can accurately measure the AC voltage of arbitrary waveforms and has nothing to do with the distortion of waveforms.
