Electrical Measurement: Multimeters Overview

Study Notes

Analog multimeters provide continuous readings, allowing detection of sudden signal changes.
They are affordable and can perform all measurements with a single meter.
Analog multimeters are bulky and have multiple scales, which can lead to confusion.
They have low input resistance and are less accurate than digital multimeters.

Digital multimeters measure various electrical quantities, including voltage, current, resistance, temperature, frequency, capacitance, continuity, and transistor gains.
They use a function switch to select different measurement modes, like AC or DC voltage, current, or resistance.
A D.C. voltage divider, consisting of a chain of resistors, measures DC voltages within different ranges.
A rectifier converts AC voltage to DC voltage proportional to the RMS value, using the same resistance chain for both AC and DC voltage measurements.
Current sensing resistors measure current by measuring the voltage drop across them, which is proportional to the current being measured.

Digital voltmeters measure DC voltage with a basic range of 2V. They are often incorporated as chips within DMMs.

CROs are electronic instruments that transform electrical signals into visual signals for analysis.
They incorporate a Backlighting Unit (BLU) that uses fluorescent lamps to illuminate the LCD panel.
The Housing Panel houses the LCD panel and BLU panel in parallel, containing the CCFL rows.
CROs also include reflectors, brightness controllers, and diffusers.

Analog displays use a moving pointer to indicate measurements on a graduated scale.
Digital displays do not have moving parts and display measurements numerically.

Light-Emitting Diode (LED) displays utilize LEDs that emit light when forward biased, with color determined by the material used.
Liquid Crystal Display (LCD) displays also rely on LEDs but differ from LED displays in their BLU technology.