Choosing Between Digital and Analog Multimeters
1.Analog multimeters offer lower reading accuracy, yet the pointer swing is intuitive and visual. The speed and amplitude of deflection can objectively reflect subtle changes in the measured quantity. For example, it clearly shows slight fluctuations on a TV data bus (SDL) during data transmission. Digital multimeters display readings directly; however, rapid numerical changes often appear erratic and are difficult to observe continuously.
2.Analog multimeters usually contain two batteries: a low‑voltage 1.5 V cell and a high‑voltage 9 V or 15 V battery. On analog meters, the black probe is positive relative to the red probe. Digital multimeters generally use a single 6 V or 9 V battery.In resistance mode, analog multimeters supply a much higher probe output current than digital models. The R×1 range can produce a loud click sound from a speaker, while the R×10k range can even light up an LED.
3.In voltage measurement mode, analog multimeters have lower internal resistance and poorer accuracy. They often fail to deliver reliable results in high‑voltage and micro‑current circuits, because their low internal resistance loads and disturbs the circuit under test. For instance, when measuring the accelerating anode voltage of a TV picture tube, readings will be significantly lower than the actual value.Digital multimeters feature extremely high internal resistance at the megaohm level, causing negligible loading on the circuit. Nevertheless, their ultra‑high input impedance makes them susceptible to induced voltage interference; measured values may become unstable or false in environments with strong electromagnetic interference.
4.In summary, analog multimeters are more suitable for measuring analog circuits with relatively high current and high voltage, such as televisions and audio power amplifiers. Digital multimeters work better for low‑voltage, small‑current digital circuits, such as pagers and mobile phones. Neither type is universally superior; users may select analog or digital multimeters according to practical application requirements.
