Digital multimeters come in a variety of different types, each designed for specific tasks and measurements. The most common type of DMM is the handheld DMM, which is small and portable, making it ideal for taking measurements in the field. Benchtop DMMs are larger and more expensive but offer more features and higher accuracy.

Multimeters can also be classified by their input type. Most DMMs will have both AC/DC voltage inputs, but some may only have one or the other. AC multimeters are designed for measuring alternating current readings, while DC multimeters are designed to read direct current measurements. There are also special types of multimeters, such as true RMS multimeters, which are designed for measuring AC quantities that have a sinusoidal or non-sinusoidal waveform.

Digital multimeters can also be classified by the range of values they can measure. Some DMMs can only measure small ranges, while others have a much wider range. The range of a DMM is typically expressed in terms of volts, amperes, or ohms. For example, a DMM with a range of 0-1000 V can measure voltages from 0 to 1000 volts.

A DMM typically has various controls that allow the user to select the desired measurement mode and range. They also have a variety of connections that allow them to be used with different  devices and circuits.

The most common types of controls on a digital multimeter are:

1. Mode selector. This switch selects the desired measurement mode, such as AC voltage, DC voltage, or resistance. The mode selector switch is usually located on the front of the multimeter.
2. Range selector. This is used to select the desired measurement range of a particular mode. The range selector switch is also located on the front of the multimeter.
3. Ports. These are used to plug in leads or other probes used in testing. The ports are often located at the bottom of the meter.

Digital multimeters also have a variety of different input types that allow them to be used with a variety of different devices and circuits. The most common input types are AC voltage and DC voltage, but some multimeters also have specific inputs for measuring alternating current that has a non-sinusoidal waveform.

They also have various display types that allow them to show the measured quantity in either digital or analog form. Some multimeters also have a built-in analog meter that can be used to visualize the measurement.

The polarity of analog and digital multimeters is different because they measure voltage in different ways. Analog multimeters measure voltage by applying a small current to the circuit and measuring the voltage drop across a resistor. This voltage drop is caused by the current flowing through the resistor. Digital multimeters, on the other hand, measure voltage by sampling the voltage at the input terminals and converting it to a digital value. The direction of the digital conversion determines the polarity of the digital multimeter.

Digital multimeters offer several advantages over their analog counterparts. Some of the most significant advantages are:

• They give much more accurate readings than analog multimeters. This is because digital multimeters use digital technology to take measurements, which eliminates the need for analog-to-digital conversion. This results in more accurate measurements, particularly when measuring AC quantities.
• Another advantage of digital multimeters is that they are much easier to use than analog multimeters. With a digital multimeter, you simply select the function you want to measure and then connect the leads to the appropriate terminals. There is no need to worry about setting the correct range or dialing in the correct measurement. Simply select the function and let the multimeter do the rest.
• Depending on the model, digital multimeters also offer several other benefits, such as the ability to store measurements in memory, take multiple readings at once, and print out measurements. These features can be extremely helpful when performing complex measurements or when taking measurements over a period of time.

When choosing a DMM, you should consider the following factors:

1. Accuracy: A digital multimeter's accuracy is the degree to which the multimeter can measure a quantity. The accuracy is typically expressed as a percentage of full scale (F.S.). For example, if a digital multimeter has an accuracy of 0.5% F.S., it can measure a quantity to within 0.5% of the full scale.
2. Resolution: A digital multimeter's resolution is the smallest change in quantity that the multimeter can measure. The resolution is typically expressed as a percentage of full scale (F.S.). For example, if a digital multimeter has a resolution of 0.1% F.S., it can measure changes in the quantity to within 0.1% of the full scale.
3. Range: The range of a DMM is the range of values the multimeter can measure. The range is typically expressed as a percentage of full scale (F.S.). For example, if a digital multimeter has a range of 0.5% F.S., it can measure values from 0% to 0.5% of the full scale.
4. Sampling rate: The sampling rate of a multimeter is the rate at which the multimeter takes measurements. The sampling rate is typically expressed as a number of samples per second (S/s). For example, if a digital multimeter has a sampling rate of 1 S/s, it takes one measurement every second.

Accuracy and precise readings are critical when working with electrical quantities. Digital multimeters offer a high degree of accuracy, making them the preferred choice for many applications.

They are available with an overall accuracy of:

• 0.1%
• 0.2%
• 0.5%.

The 0.5% and 0.2% accuracy levels are suitable for most general-purpose applications. The 0.1% accuracy level is typically only necessary for industrial or scientific applications.

As we have looked at, a digital multimeter is a valuable tool for troubleshooting circuits and verifying the operation of electrical and electronic circuits. If you need to test or measure quantities such as voltage, current or resistance, a digital multimeter is the right tool for the job.

To learn more about the features of used Keysight Multimeters and to see the wide variety of products we sell at discounted rates, visit Keysight Used Equipment.