Analog vs. Digital Multimeter: Key Differences

There are two main types of multimeters: analog and digital. The distinction lies in their measurement and display methods. Let’s explore both.

Analog Multimeter

In an analog multimeter, the value of the quantity being measured is represented by the continuous deflection of a pointer across a scale.

Inside, you’ll find a current-measuring moving coil meter with appropriate internal resistors. These resistors are brought into the circuit based on the selected range via a switch. It’s used to measure AC and DC current and voltage, as well as resistance. Some multimeters can even measure capacitors and transistors. The actual resistance of an analog multimeter depends on the chosen range and its sensitivity.

Figure 1: Analog Multimeter Type

Digital Multimeter

A digital multimeter is an electronic multimeter that displays measurements as digital decimal values, typically on an LCD screen.

The measurement is processed by an ADC (analog-to-digital converter). To measure voltages of lower magnitudes, the signal is often amplified before being displayed. For fluctuating voltage measurements, a latch circuit is used to hold the current sample until the next sample is measured and displayed.

Figure 2: Digital Multimeter Type

Key Differences

Here’s a breakdown of the important differences between analog and digital multimeters:

• Input Resistance: A digital multimeter maintains a constant input resistance across all measurement ranges, unlike its analog counterpart.
• Accuracy: Digital multimeters generally provide better accuracy than analog multimeters, which can be prone to errors due to subjective pointer readings.
• Frequency Range: The highest frequency an analog multimeter can handle using rectifiers on the AC range is around 2 kHz. Digital multimeters offer a much higher frequency range.