Digital multimeters (or multi-meter) are instruments that are used to measure electrical quantities such as:

• voltage
• current
• resistance
• frequency
• temperature
• capacitance
• time period measurements

Basic functionality includes measurement of potential in volts, resistance in ohms, and current in amps. Multimeters are used to find electronic and electrical problems. Advanced units come with more features such as capacitors, diodes, and IC testing modes.

Specifications

Digital multimeters are generally bench top or handheld. Bench-top models can also be portable via handles and wheels. Handheld multimeters are specifically designed to be used while holding (i.e., can be operated with one hand). Digital multimeters display information on a digital screen. Commonly, they have between three and six digits, but some units come with larger screens that can display seven or more digits. The fastest sampling rate is also important to consider.

Types

Specific measurements made by digital multimeters include:

• DC voltage
• AC voltage
• DC current
• AC current
• resistance
• capacitance
• frequency range
• time period
• special measurements

Special measurements include continuity check, audible continuity, diode test, maximum, minimum, or peak spike measurement, RTD temperature measurement, thermocouple temperature, and transistor test. Continuity checks will give an indication to the user that a closed loop exists due to the probes touching each other. Digital multimeters with audible continuity will beep when probes are touching each other. Diode tests will check to see if a diode is good or bad. Digital multimeters with maximum, minimum, or peak spike measurement can measure and display when these events occur. Some multimeters are capable of measuring temperature with either an RTD or thermocouple probe. Multimeters with a transistor test are capable of examining a transistor and telling the user where the emitter, collector, and base are located. When searching for digital multimeters, it is important to consider the measurement range for whichever value is being measured.

Features

Common features for digital multimeters include battery power, analog bar graph, dB readings, auto-ranging, adjustable sampling rate, programmable, data acquisition, data storage and logging, removable data storage, and triggering. Devices with battery power can be operated without plug-in power. Output options for digital multimeters include GPIB, IEEE 488, RS232, BCD, and D/A. An important environmental parameter to consider when searching for multimeters is the operating temperature.

Related Information

CR4 Community—Digital Multimeter Portable

CR4 Community—Multimeter Use Question

Engineering360—Analog Multimeters Information

Image credit:

Alex P. Kok / CC BY-SA 4.0