Pointer multimeter and the selection method of digital multimeter
1. The reading accuracy of the pointer meter is poor, but the process of pointer swing is intuitive, and its swing speed and amplitude can sometimes objectively reflect the measured size (such as the slight jitter of the data bus (SDL) of the TV set when transmitting data); The reading of digital meter is intuitive, but the process of digital change looks messy and not easy to watch.
2. Generally, there are two batteries in the pointer meter, one with low voltage of 1.5V and the other with high voltage of 9V or 15V, and its black stylus is the positive terminal relative to the red stylus. Digital meters often use a 6V or 9V battery. In the resistance range, the output current of the stylus of the pointer meter is much larger than that of the digital meter. Using R×1Ω range can make the speaker make a loud "beep" sound, and using R×10kΩ range can even light up the light emitting diode (LED).
3. In the voltage range, the internal resistance of the pointer meter is relatively small compared with the digital meter, and the measurement accuracy is relatively poor. It is even impossible to measure the high-voltage micro-current in some occasions, because its internal resistance will affect the circuit to be measured (for example, the measured value will be much lower than the actual value when measuring the voltage of the acceleration stage of the TV picture tube). The internal resistance of digital meter voltage file is very large, at least in the order of megaohms, which has little influence on the circuit under test. However, the extremely high output impedance makes it vulnerable to the induced voltage, and the measured data may be false in some occasions with strong electromagnetic interference.
4. In short, the pointer meter is suitable for the measurement of analog circuits with relatively high current and high voltage, such as TV sets and audio amplifiers. Digital meters, such as mobile phones, are suitable for digital circuit measurement with low voltage and small current. Not absolute, you can choose a pointer table and a number table according to the situation.
