A digital multimeter is an instantaneous sampling instrument. It uses a sample taken every 0.3 seconds to display the measurement results. Sometimes, each sampling result is only very similar and not exactly the same, which is not as convenient for reading the results as the pointer type.
Due to the use of an operational amplifier circuit inside the digital multimeter, the internal resistance can be large, often at 1M ohms or greater. (i.e. higher sensitivity can be obtained). This allows for less impact on the tested circuit and higher measurement accuracy.
The output voltage of a digital multimeter is relatively low (usually not exceeding 1 volt). It is inconvenient to test some components with special voltage characteristics (such as thyristors, light-emitting diodes, etc.).
The output voltage of the pointer multimeter is relatively high, such as 10.5 volts, 12 volts, etc. The current is also large (such as MF-500 * 1 ohm range with a maximum of about 100 milliamperes), which can facilitate testing of thyristors, light-emitting diodes, etc.
1. The reading accuracy of the pointer meter is poor, but the process of pointer oscillation is relatively intuitive, and the amplitude of its oscillation speed can sometimes objectively reflect the measured size (such as the slight jitter of the TV data bus (SDL) during data transmission); The reading on the digital meter is intuitive, but the process of changing the numbers looks messy and not easy to watch.
2. There are usually two batteries in a pointer meter, one with a low voltage of 1.5V and the other with a high voltage of 9V or 15V. The black pen is relatively positive compared to the red pen. A digital meter usually uses a 6V or 9V battery. In the resistance range, the output current of the pointer meter is much larger than that of a digital meter, using R × 1 Ω gear can make the speaker emit a loud "click" sound, using R × 10k Ω gear can even light up light-emitting diodes (LEDs).
3. In the voltage range, the internal resistance of a pointer meter is relatively small compared to a digital meter, and the measurement accuracy is relatively poor. In some situations where high voltage and micro current are present, it is even impossible to accurately measure them because their internal resistance can affect the circuit being tested (for example, when measuring the acceleration stage voltage of a television picture tube, the measured value may be much lower than the actual value). The internal resistance of the voltage range of the digital meter is very high, at least at the megaohm level, and has little impact on the circuit being tested. But the extremely high output impedance makes it susceptible to the influence of induced voltage, and the data measured in some places with strong electromagnetic interference may be false.
4. In short, pointer meters are suitable for measuring analog circuits with relatively high currents and voltages, such as television sets and audio amplifiers. Digital meters are suitable for low voltage and low current digital circuit measurements, such as BP machines, mobile phones, etc. Not absolute, you can choose a pointer table and a digital table according to the situation.
