Will Digital Multimeters Replace Analog Pointer Multimeters
In addition to the different display methods, there is also a biggest difference between the two, which is the internal resistance. The internal resistance of a digital multimeter is more than two orders of magnitude higher than that of a pointer multimeter, and the internal resistance of a good pointer meter is not as high as that of the worst digital meter. This is also one of the reasons why digital meters measure more accurately than pointer meters.
However, high internal resistance may not always be an advantage. For example, when measuring resistance, a multimeter must provide current to flow through the resistance in order to obtain the resistance value by measuring the resistance voltage. At this time, the current provided by a digital meter is often very small, in the microampere level, while a pointer meter is in the milliampere level. If you use a resistance level to measure the leakage resistance of a capacitor, it is too slow for the digital meter to fill the microampere level capacitor with this current, It is almost impossible to measure, and a pointer meter can quickly charge the capacitor and detect leakage.
However, the small output current characteristic of a digital meter is convenient, accurate, and unique when measuring resistance values online. Due to the small output current, the surrounding online capacitors, inductors, and transistors have very small shunt, so measuring resistance values online is more accurate and hassle free. Generally, it is not necessary to weld open solder joints to measure whether the resistance value is normal.
For example, when measuring the PN junction of nonlinear devices, the current provided by a digital meter often differs significantly from the actual working current, resulting in inaccurate judgment. At this point, the pointer table is very useful.
Two measurement tools, digital meters, can replace pointer meters more in the production measurement and control process. But in fields such as technology development and maintenance, pointer watches still play an irreplaceable role.
