Your application will determine how you choose a multimeter.
There are many types of multimeters in the market nowadays, and the specific choice of multimeter depends on one's own use. However, regardless of which type of multimeter is chosen, it is definitely not advisable to choose an ancient pointer type multimeter. A multimeter like MF47 is far inferior to a digital multimeter in terms of measurement accuracy and functionality, and some of its gear scales are non-linear, which brings some inconvenience to beginners' quick readings and sometimes makes it easy to read measurement results incorrectly. Therefore, this article only introduces the selection of a digital multimeter.
A regular 3/1/2 digit multimeter.
If the questioner purchases a multimeter with low usage frequency and only occasionally uses it at home to measure AC220V voltage or battery voltage, as well as the continuity of the circuit, then spending 30-40 yuan to purchase a regular 3/1/2 digit multimeter is sufficient. Ordinary digital multimeters such as DT830 and UT33D can measure AC/DC voltage, current, and resistance, and come with diode and buzzer settings, which are sufficient for general measurement and simple maintenance at home.
By the way, when purchasing this type of multimeter, don't expect it to be cheap. Instead, buy those digital multimeters that cost over ten yuan. These cheap ones have poor reliability and save on internal components. The AC voltage range of a good DT830 multimeter uses a TL062 operational amplifier connected to a precision rectifier circuit, which can accurately measure low-frequency AC voltages in the millivolt range. However, those multimeters of the same model that cost more than ten yuan omit the TL062 operational amplifier and use a 1N4007 diode rectifier, so their AC voltage range can only measure AC voltages above 1V, resulting in significant errors in measuring millivolt level AC voltages.
Multi functional digital multimeter.
If the questioner is engaged in electrical repair and needs to measure multiple electrical parameters, it is recommended to purchase a fully functional digital multimeter. This type of multimeter is available in prices ranging from 70-80 to hundreds of yuan. Most digital multimeters in this price range come with capacitor, frequency, and transistor beta settings, which can measure capacitors of 2000~20000 μ F and frequencies of 2~20MHz. Some digital multimeters can also measure conductivity, duty cycle, temperature, and inductance.
A digital multimeter can measure frequencies up to 20MHz in the frequency range and 2000M Ω in the resistance range. Its temperature measurement range is -20~1000 ℃, and it can also measure inductance, with a maximum measurement of 20H. It is very convenient for measuring various inductance coils.
True RMS digital multimeter.
A regular digital multimeter can only measure low-frequency sine wave AC voltage between 40-400Hz. If the waveform of the measured AC voltage is a triangular wave, rectangular wave, or other waveform, the reading error will be significant. 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 labeled "True RMS" on the panel and uses an AD736 true RMS measurement IC internally to measure AC voltage. It can accurately measure AC voltage of any waveform and is independent of waveform distortion.
