Digital Multimeters

What Is a Digital Multimeter?

A digital multimeter is a device used to measure current, voltage, resistance and continuity in circuits and in components. Some have other measurement capabilities, as well, but most have at least these four. These functions are all combined into one device, making it much easier for people troubleshooting components to try to find faults. They are also used simply to analyze circuits, from the resistance value of components that may be unlabeled and beyond.

Digital multimeters are the successors to analog multimeters, which were outfitted with a needle on a painted meter from which the operator took readings. Digital multimeters have a numerical display that allows for more precise readings, though they tend to perform more poorly than analog meters when trying to gauge a rapid fluctuation in value.

In every other regard, Digital multimeters are significant improvements on analog multimeters. They are easier to read and many of them take care of some of the tasks associated with using an analog multimeter, such as figuring out the range of values being measured, automatically.

 

How Does a Digital Multimeter Function?

While a digital multimeter measures several different electrical values, all of those measurements are based on a measurement of voltage. This measurement is used to calculate other measurements. Measurements other than electrical ones—temperature, etc.—are measured otherwise.

Because the digital multimeter is measuring an analog value – voltage – an analog-to digital converter is utilized in the device that samples that data and gives a digital interpretation of the reading. This displays on the screen for the user.

The multimeter will generally have several different inputs and one output, usually labeled COM. The negative lead always stays in the COM input. Depending upon what is being measured, the positive lead is switched between various inputs designed for the purpose. There will typically be a specific input for measuring resistance, voltage and amperage, with the latter most oftentimes having multiple inputs to accommodate greater and lesser amounts of current and less and more precise measurements. Some multimeters have a separate input for continuity and others combine that input with another.

Digital multimeters are generally advanced enough to be much more convenient to use than analog multimeters. On the analog models, the user would have to know in advance which range of values they would be working with and set their multimeter accordingly. Today, digital multimeters will automatically make this calculation. Most users will measure current starting out with the highest range of values that their multimeter can handle and only go lower when the current level proves safe to do so.

Most measurements are made by simply bringing the probes into contact with the positive and negative side of a component or circuit. The exception to this is the measure of current, which requires that the multimeter be placed in series in the circuit to take the reading.

 

What Is a Digital Multimeter Used For?

One of the most common uses of a digital multimeter is in troubleshooting. They have a convenient system of leads, which consist of a pair of probes that can easily be put into contact with electronic components within a circuit board, isolated electronic components and other electronic hardware.

Digital multimeters are also used to take simple readings when a value is unknown. For example, to determine whether a household socket is outputting the proper voltage, a digital multimeter can be inserted into the receptacles, allowing a reading to be taken.

In complicated circuits, a digital multimeter can be used to track down a faulty component among a vast array of components. One of the exceptions to this is resistors, which typically have to be isolated from a circuit to get a proper resistance value. The continuity functionality, however, is extremely useful in simply determining whether a circuit is shorted or otherwise unintentionally opened.

The continuity measuring feature on digital multimeters is also frequently employed to determine whether or not a cable is good or bad. This can eliminate a great deal of time hunting down broken equipment.

Some multimeters come with even more measurement capabilities, such as the ability to measure capacitance and to measure frequency. Some older meters are also outfitted with temperature sensors, which can be very helpful in determining whether components are operating within their specified ranges.

 

Which Companies Produce Digital Multimeters?

Digital multimeters are manufactured by many different companies. Those intended for professional use, however, need to be precision devices and, because of that, the manufacturers that sell directly to industry and other demanding sectors tend to be fewer. They include the following, among others.

 

Agilent Technologies

This company is based in the US and makes measurement devices of all types.

 

Aim-TTi

Aim-TTi stands for Thurlby Thandar Instruments and Aim Instruments. They are based in the US and make several different types of measurement equipment.

 

Amprobe

This manufacturer produces many goods for the construction market, for HVAC systems and for related industries. They make many testers and meters.

 

Chauvin Arnoux

This French company specializes in making all manner of measurement equipment.

 

Fluke

A testing and measurement equipment manufacturer that is headquartered in the US.

 

Gossen Metrawatt

This manufacturer makes many different types of electrical safety testers, measurement tools and more.

 

Hameg

This company specializes in measurement instruments designed for the laboratory, but has many different models.

 

ISO-TECH

ISO-TECH makes oscilloscopes and many other types of electrical testing instruments.

 

Keithley

This is another manufacturer that specializes in test instruments. They are headquartered in Ohio.

 

What Do the Following Properties Define?

 

Absolute Maximum AC Current Measurement

This is the highest alternating current amperage that the multimeter can handle. The multimeter will likely fail – or at least blow a fuse – if it is exposed to a higher current than this. Most users will start with the highest range of amperage when measuring an unknown amount of current and then step down as required.

 

Absolute Maximum AC Voltage Measurement

This is the highest voltage that the multimeter can handle without having a failure or sustaining some sort of damage.

 

Absolute Maximum DC Current Measurement

This is the highest direct-current amperage that the multimeter can work with and still take an accurate reading and not be subject to sustaining damage.

 

Absolute Maximum DC Voltage Measurement

This value corresponds to the highest DC voltage that the multimeter can measure.

 

Absolute Maximum Resistance Measurement

Expressed in ohms, this defines the largest amount of resistance that the multimeter can read.

 

Absolute Maximum Temperature Measurement

On multimeters outfitted with temperature sensors, this is the highest temperature that the multimeter can read safely.

 

Absolute Maximum Capacitance Measurement

This is the highest level of capacitance, measured in farads, which the multimeter can read.

 

Maximum Frequency

This corresponds to the highest frequency that the multimeter can read.

 

What Is Model Number?

This corresponds to the model number of a given digital multimeter. It provides an easy way to sort through the options given by a specific manufacturer, given that some of them offer many different products.

 

What Is Considered True RMS?

RMS is a measurement of how much the potential and applied voltage has. In practice, this measurement is taken as a way to determine how much power dissipation occurs in a resistor.

 

Which Multimeter Types Exist?

 

Bench

Bench digital multimeters are designed to be used in laboratory settings, shops and so forth. They are devices that are engineered to be rich in features rather than compact or easily moved from place to place.

 

Handheld

Because digital technology is capable of delivering many features in small devices, handheld digital multimeters are much more powerful than they were in the past. However, they commonly have fewer features than bench models but are easily held in the hand and taken in a toolbox. These are also commonly used by hobbyists who only need a simple multimeter to perform many of their projects.

 

Which Functions Are Measured with a Digital Multimeter?

Digital multimeters, because of the power of the technology in them, can be enormously varied in terms of the functions that they can actually measure. In addition to the aforementioned common features, some of them are able to measure decibel levels, frequencies, diodes, are able to test batteries and perform other functions. This makes them extremely versatile and, even among the handheld models, sophisticated measurements can typically be taken in the field.

 

What Does the Safety Category Define for a Digital Multimeter?

Safety categories are vital information about multimeters. They define where the device can be used safely and under which circumstances. A Category I digital multimeter, for example, is only used on electronics that are not directly connected to mains power. At the other end of the spectrum, Category IV multimeters can be used on circuits that have very high levels of current. The category of the digital multimeter determines how much voltage can safely be applied to the device.

 

Which Application Can Digital Multimeter Be Used for?

Applications for digital multimeters are, essentially, inclusive of any application that involves having to know the condition of a circuit or component. This includes work in automotive, HVAC, residential electrical, marine, hobbyist, industrial and other applications. These are among the most common electrical tools in use.

 

What Do the Following Parameters of a Digital Multimeter Define?

 

Best AC Current Accuracy

This is a percentage value that represents how accurately the device can measure AC current.

 

Best AC Voltage Accuracy

This corresponds to the accuracy with which the device can measure AC voltage, again expressed in percentages.

 

Best Capacitance Measurement Accuracy

This specification refers to how accurately the device measures capacitance.

 

Best DC Current Accuracy

This indicates the accuracy of the device when measuring current across a DC circuit.

 

Best DC Voltage Accuracy

The accuracy with which the device can measure DC voltage.

 

Best Resistance Measurement Accuracy

This describes how accurately the device measures resistance in a circuit or component.

 

Best Temperature Measurement Accuracy

The most accurate temperature reading that the device can be expected to give is defined by this number.

 

Which Resolutions Do the following determine?

Resolution refers to how small the increments the device makes are, a function of converting analog input to digital information. Note that some multimeters have displays that can show many digits, but their accuracy may not be as great as the number of digits that the display shows. This is not an issue in professional quality multimeters, however.

 

AC Current Measurement Resolution

This is the smallest increment of AC current that can be measured by the device.

 

AC Voltage Measurement Resolution

The smallest variation in alternating current voltage that can be measured by the device is defined by this number.

 

Capacitance Measurement Resolution

This is the precision with which the device can measure capacitance in terms of how many numbers can be expressed.

 

DC Current Measurement Resolution

This is the smallest increment of DC current the device can measure.

 

DC Voltage Measurement Resolution

On DC circuits, this is the smallest measurement of voltage the device can make accurately.

 

Resistance Measurement Resolution

The smallest decimal of resistance that a device can measure is expressed in this specification.

 

Temperature Measurement Resolution

This is the maximum resolution of temperature measurements that can be taken by the device.

 

Which Display Types Exist for Digital Multimeters?

Digital multimeters come with different types of displays, generally selected depending upon the complexity of the device. LCD screens and LED screens both provide cost effective solutions that can offer durable quality and reliable service. VGA screens and other options may be used in other circumstances or where complex information needs to be displayed.

 

What Is Considered the Safety Category Level and Safety Category Voltage?

These specifications describe the Category of the device, described above, which dictates under which circumstances it can be used. The Safety Category Voltage describes how much voltage in both AC and DC circuitry the device can safely measure.

 

Which Battery Types Exist for Digital Multimeters and what Is the Battery Life?

Digital multimeters can operate on commonly sized batteries, such as AA and AAA models. The most portable devices can actually function on only one of either type of battery. Watch batteries and rechargeable batteries are other options for these devices.

The battery life describes how long the battery will be able to sufficiently power the device under normal operation. Most of these devices offer hundreds of hours of battery life.

 

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