Introduction to the Differences between Analog Multimeters and Digital Multimeters
An analog multimeter can basically measure DC voltage, AC voltage, DC current, and resistance. Except for some special products, they cannot measure AC current. The features of the latest analog multimeters include extended measurement functions due to the installation of amplifiers (especially suitable for small voltages and currents), the function of measuring capacitance, and the function of a zero-center multimeter. To enhance operability and usability, certain products incorporate an automatic range function, an automatic polarity switching function, and a structure with a box for storing test leads. Some testers can measure the hFE (DC current amplification factor) of transistors and measure temperature using a temperature probe.
An analog multimeter is an average-value type instrument, which has intuitive and vivid reading indications. On the other hand, a digital multimeter is an instantaneous sampling type instrument. It samples every 0.3 seconds, and the results are only very close but not exactly the same, making it not very convenient to read the results.
Generally, an analog multimeter does not have an amplifier inside, so its internal resistance is relatively small. For example, the MF-10 model has a DC voltage sensitivity of 100 kΩ/V, which is quite outstanding. The MF-500 model has a DC voltage sensitivity of 20 kΩ/V. In contrast, due to the operational amplifier circuit used inside a digital multimeter, its internal resistance can be made very large, often reaching 1 MΩ or more. This makes its impact on the measured circuit smaller and the measurement accuracy higher.
Because of its relatively small internal resistance and the use of discrete components to form the shunt and voltage division circuits, the frequency characteristics of an analog multimeter are uneven (compared with digital multimeters), while the frequency characteristics of an analog multimeter are relatively better in a certain sense.
The internal structure of an analog multimeter is simple, so its cost is low, its functions are few, maintenance is easy, and its ability to withstand overcurrent and overvoltage is relatively strong. A digital multimeter, on the other hand, uses various circuits such as oscillators, amplifiers, frequency dividers, and protection circuits inside, so it has more functions. For example, it can measure temperature, frequency (within a relatively low range), capacitance, inductance, or even act as a signal generator, etc. Since its internal structure mostly uses integrated circuits, its overload capacity is poor, and it is generally not easy to repair after being damaged.
An analog multimeter has a relatively high output voltage and large current (for example, the MF-500 *1Ω range can reach up to about 100 mA), which makes it convenient to test components such as thyristors and light-emitting diodes. In contrast, a digital multimeter has a relatively low output voltage (usually not exceeding 1 volt), which makes it inconvenient to test some components with special voltage characteristics (such as thyristors and light-emitting diodes).
