Blog Digital Multimeters (DMMs): How They Work and Their Role Today

Digital Multimeters (DMMs): How They Work and Their Role Today

The Definitive Guide To Using Multimeters

The Definitive Guide To Using Multimeters

What Is a Digital Multimeters (DMM)?

A digital multimeter (or DMM for short) is a high-tech tool used to measure electricity. It contains a digital readout for measuring things like voltage, current, resistance, capacitance, frequency, and more.

Unlike an analog multimeters that uses mechanical movements and analog scales, DMMs use digital displays, typically consisting of a liquid crystal display (LCD) or LED screen, to provide precise numerical measurements.

DMMs can also offer additional features such as data logging, peak hold, continuity testing with audible beeps, diode testing, temperature measurement with external probes, and more. Some advanced DMMs may even have built-in wireless connectivity or USB ports for data transfer and integration with computer software.

The Definitive Guide To Using Multimeters

This is the fifth article in our series, The Definitive Guide to Using Multimeters.

This article discusses the digital multimeter (DMM) and its relative strengths and weaknesses.

In This Article:

Digital Multimeter Components
How Does a Digital Multimeter Work?
Why Digital Multimeters Shine Today
Digital Multimeter FAQs

If you missed the start of the series: What Is a Multimeter?: The Definitive Guide to Multimeters, check it out now! You will be able to work your way back to this article quite quickly.

The Definitive Guide to Multimeters: Table of Contents

Digital Multimeter Components

The main components of a typical digital multimeter (DMM) are:

Display
Selector Switch/Buttons
Range Button
Power Button
Probes
Input Jacks
Battery Compartment
Microprocessor/ASIC
Internal Circuitry

Display

The display is one of the essential components of a digital multimeter. It can be an LCD (Liquid Crystal Display) or an LED (Light-Emitting Diode) screen. The display shows the measured values and other relevant information, such as units, symbols, and mode indicators.

Selector Switch/Buttons

Digital multimeters have a selector switch or buttons that allow you to choose the measurement function and range. The switch/buttons are used to select options such as voltage (AC or DC), current (AC or DC), resistance, capacitance, frequency, and temperature.

Range Button

Power Button

Digital multimeters have a power button to turn the device on and off, helping conserve battery life when the multimeter is not in use.

Probes

Digital multimeters typically come with detachable probes for making electrical connections. The probes consist of a red (positive) and a black (negative) lead with metal tips or clips. These probes are used to connect the multimeter to the circuit or component being measured.

Input Jacks

Digital multimeters have input jacks where the probes are connected. The jacks are color-coded to match the color of the probes, typically red for positive and black for negative. The input jacks are labeled according to the measurement type, such as voltage, current, or resistance.

Battery Compartment

DMMs are powered by batteries, and they have a battery compartment for easy replacement when needed. The compartment is typically located on the back or bottom of the multimeter.

Microprocessor/ASIC

Digital multimeters contain a microprocessor or an Application-Specific Integrated Circuit (ASIC) that handles the measurement processing, conversion, and display functions. The microprocessor interprets the input signals and calculates the appropriate measurement values for display.

Internal Circuitry

Digital multimeters have internal circuitry that includes amplifiers, analog-to-digital converters (ADC), and other components necessary for signal conditioning, measurement accuracy, and data processing.

How Does a Digital Multimeter Work?

1. Probes Connected

When the user of the multimeter connects the probes to the circuit or component being measured, an input signal is created.

2. Input Signal Conditioned

The input signal from the probes is then conditioned by the multimeter’s internal circuitry. This circuitry may include amplifiers, filters, and other components to ensure accurate and reliable measurements.

3. Signal Converted

The conditioned signal is converted from an analog voltage or current into a digital representation using an analog-to-digital converter (ADC). The ADC samples the signal at regular intervals and assigns a digital value to each sample based on its amplitude.

4. Calculations Performed

Once the signal is digitized, it undergoes further processing by the multimeter’s microprocessor (or ASIC). The microprocessor performs calculations and adjustments based on the selected measurement function, range, and any additional features enabled.

5. Analog-to-Digital Conversion

An ADC samples the signal and converts it into a digital value based on amplitude.

6. Processing

The microprocessor or ASIC calculates the measurement, adjusting for the selected function (e.g., resistance) and range.

7. Measurement Displayed

Finally, the processed measurement value is sent to the multimeter’s display. The digital display shows the measured value, along with units, symbols, and any other relevant information.

Why DMMs Shine Today

DMMs offer unmatched precision and versatility, with 2025 models boasting:

Accuracy: Typically ±0.5% or better, compared to ±2% for analog multimeters.
Features: Auto-ranging, data logging, true-RMS, and IoT connectivity for real-time monitoring.
Applications: Diagnosing EV battery systems, testing solar inverters, or prototyping IoT sensors.

Limitations: Reliance on batteries and potential screen readability issues in bright sunlight.

Case Study: A technician uses a 2025 DMM with true-RMS to troubleshoot a variable-speed motor drive, ensuring accurate readings for non-sinusoidal waveforms.

Digital Multimeter FAQs

Can DMMs measure both AC and DC? Yes, with dedicated settings for AC/DC voltage and current.
What’s auto-ranging? The DMM automatically selects the optimal measurement range, simplifying use.
Why use true-RMS today? It ensures accurate AC measurements for complex waveforms in modern electronics.
Are DMMs better than analog multimeters? For most tasks, yes, due to higher accuracy and advanced features.

Conclusion

Digital multimeters are the backbone of 2025 electronics, offering precise measurements of voltage, current, resistance, and beyond, with cutting-edge features like IoT integration. Whether you’re testing a smart home circuit or an EV battery, DMMs deliver reliability and versatility. Explore their capabilities, compare them to analog models, or start measuring with confidence today.

What’s Next: The Definitive Guide to Multimeters

Now that we know all about digital multimeters, its time to explore the differences between digital multimeters and their brother, analog multimeters.

In the next section, we will dive explore these differences in detail and set you up to make the best decision of what is right for you. Lets get started and head to Section 6: Analog vs. Digital Multimeters.

ISO/IEC 17025 Accredited Multimeter Calibration

At Fox Valley Metrology, we specialize in precision multimeter calibration services for every make and model of multimeter across all our nationwide locations. Our ISO/IEC 17025 accreditation ensures that each instrument is tested to the highest standards. From in-lab service to on-site calibration, we tailor our offerings to fit your schedule and needs.

✓ ISO 17025 accredited calibration vendor
✓ Broadest calibration scope in the industry
✓ 3-5 day turnaround time for laboratory calibrations
✓ Pickup and delivery service options available
✓ Onsite multimeter calibration service options

About the Author

Ryan Pollack

Ryan joined Fox Valley Metrology in 2024 after graduating from UW-Oshkosh with a bachelor’s degree in Marketing and a certificate in Digital Marketing. As a recent graduate, his background strengthens Fox Valley Metrology’s outreach by introducing fresh ideas and digital strategies that engage customers in meaningful ways while building and establishing the company’s brand.