Method of Selecting between Pointer Multimeter and Digital Multimeter
The reading accuracy of a pointer multimeter is relatively poor, but the process of the pointer swinging is more intuitive. Sometimes, the swinging speed and amplitude can also objectively reflect the magnitude of the measured value (for example, when measuring the slight jitter of the data bus (SDL) of a TV set during data transmission). The reading of a digital multimeter is intuitive, but the process of the numbers changing looks rather chaotic and is not very easy to observe.
Generally, there are two batteries inside a pointer multimeter. One is a low-voltage battery of 1.5V, and the other is a high-voltage battery of 9V or 15V. The black test lead is the positive terminal relative to the red test lead. A digital multimeter usually uses a 6V or 9V battery. In the resistance range, the current output of the test leads of a pointer multimeter is much larger than that of a digital multimeter. Using the R×1Ω range can make the speaker emit a loud "da" sound, and using the R×10kΩ range can even light up a light-emitting diode (LED).
In the voltage range, the internal resistance of a pointer multimeter is relatively small compared with that of a digital multimeter, and the measurement accuracy is relatively poor. In some situations with high voltage and micro current, it may not even be possible to measure accurately because its internal resistance will affect the measured circuit (for example, when measuring the acceleration voltage of the picture tube of a TV set, the measured value will be much lower than the actual value). The internal resistance of the voltage range of a digital multimeter is very large, at least in the megohm level, and has little impact on the measured circuit. However, its extremely high output impedance makes it vulnerable to induced voltages, and the data measured in some places with strong electromagnetic interference may be false.
In general, a pointer multimeter is suitable for measuring in analog circuits with relatively large current and high voltage, such as in TV sets and audio power amplifiers. A digital multimeter is suitable for measuring in digital circuits with low voltage and small current, such as in mobile phones, etc. This is not absolute, and you can choose a pointer multimeter or a digital multimeter according to the specific situation.
