How to choose a handheld digital multimeter?
Key indicators 1. Testing principle
There are two principles of digital multimeter testing: average response and true effective value. These two testing methods respectively correspond to different types of electrical signal testing.
For DC signals or standard sine waves, both true RMS and average response instruments can accurately measure;
However, for signals containing distorted waveforms, or typical non-sinusoidal waves such as square waves, triangle waves, and sawtooth waves, only true RMS instruments can accurately measure them.
Key indicator 2. Bandwidth
Bandwidth is the AC frequency range that the digital multimeter can respond to within the accuracy range. It is not a function of measuring frequency, but the ability to reflect AC frequency response. If the frequency of the measured signal exceeds the AC bandwidth of the multimeter, the multimeter will not be able to correctly measure the AC value within the frequency response range.
For example: The test frequency range of a certain digital multimeter is 50KHZ, but the bandwidth is 500HZ. This means that when using this multimeter to test the frequency parameters of the signal, it can reach up to 50KHZ. However, when the frequency of the measured signal exceeds 500HZ, if you use this meter to test the voltage/current parameters of the signal, the test results will have a large error, so you should choose a meter with appropriate bandwidth to test the corresponding signal.
Key indicator 3. Range
The measuring range refers to the maximum value that the instrument can test in the current gear. The appropriate range must be selected based on the range of the signal value being measured. Currently, new multimeters basically integrate manual/automatic ranges, which facilitates free switching.
When choosing a digital multimeter, you should choose a meter with an appropriate range according to the actual test requirements.
Key indicator 4. Display digits and resolution
Display digits: the number of words the multimeter can display.
Usually, the number of digits that can display all digits from 0-9 are called whole digits, and the others are collectively called half digits.
