Multimeter
Multimeters come in two primary types: analog and digital. Both are designed to measure the same fundamental electrical values but differ in their measurement methods and display mechanisms. Analog multimeters, the earlier development, utilize a moving pointer over a graduated scale to indicate readings. On the other hand, digital multimeters use a Liquid Crystal Display (LCD) or Light Emitting Diodes (LED) to numerically display readings.
What is an Analog Multimeter?
Analog multimeters are constructed around an ammeter, a device for measuring electrical current in amperes. In these devices, current from the circuit being measured passes through a metal coil within a magnetic field. A pointer attached to the coil rotates, and its angle of rotation corresponds to the strength of the current. The measured values are displayed as the pointer moves across graduated scales on the meter’s face. Analog multimeters are electromechanical, converting electrical energy into mechanical movement.
What is a Digital Multimeter?
Digital multimeters, in contrast, employ digital circuits that measure current in discrete increments rather than a continuous range of values. Since digital circuits are constructed using analog components, the continuous signals need to be converted into digital form. In digital meters, this conversion involves transforming the input signal into a voltage and amplifying it for further processing. Although digital meters are inherently more accurate than analog ones, the time required for signal processing may make them less suitable for measuring values that change constantly.
Both types of multimeters are initially designed to measure direct current (DC) and require modification to measure alternating current (AC). This modification typically involves integrating a rectifier circuit that converts AC to DC and then averaging periodic measurements of the current. The average is then used to calculate the root mean square (RMS), which is reported as the AC value. True RMS multimeters, a digital subtype, use a more precise calculation based on the heat dissipated by the current against a constant resistive load
