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What is a Digital Voltmeter?

An analog voltmeter.
A digital multimeter, which can be used as an digital voltmeter.
Voltmeters are used to measure the voltage traveling between two points within a circuit.
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  • Originally Written By: Chrisc
  • Revised By: C. Mitchell
  • Edited By: C. Wilborn
  • Last Modified Date: 20 October 2014
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A digital voltmeter is a device used by many electricians and mechanical manufacturers to measure the relative voltage output of various electronic appliances. Most electronics get power through a series of voltage currents that course through them. These can be either negatively or positively charged, and usually have to exist in balance with each other in order for the product to be safe for humans to touch and interact with. Voltage problems can lead to electrical burns and shocks as well as product malfunction and “melting down.” Manufacturers often use voltmeters before their products are completed to be sure that they comply with governing laws and product codes, and larger appliances like generators often have these devices built into their control panels so that owners can keep track of energy currents during operation. Portable models are popular with electricians and repair personnel who need to understand how a device is processing energy before installing it or working on it. Digital versions are usually considered superior to older analog models, though both work in roughly the same way; the biggest different is usually how the output is translated and displayed.

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Basic Purpose

Voltmeters are used to measure the gain or loss of voltage between two points in a circuit, and they capture both alternating current (AC) and direct current (DC) outputs. Digital models, which are sometimes called DVMs, are electronic and are usually considered more modern and advanced than older analog counterparts, but they have the same goals and basic functionality, which is to display a readout of measurements at various intervals. Understanding voltage is really important for anyone doing electrical work, but volts, like electrical currents themselves, can’t actually be seen with the eyes. Using a digital tool is a quick and efficient way to make sure that everything is running the way it should, as well as to diagnose problems.

How They Work

Most voltmeters are relatively simple when it comes to basic construction. They are usually somewhat small, and consist of a basic circuitry and two wire leads that are meant to attach to whatever is being tested. The positive terminal of the meter should be connected closest to the power supply, and the negative terminal should be connected after the circuit being tested.

A digital voltmeter typically consists of an analog to digital converter (A/D) with a digital display. Originally, almost all of these sorts of devices were “analog,” which basically means that they used some form of physical qualities to measure readout, usually a dial and arrow. Digital versions typically produce a number or percentage on an electronic screen. In most cases the two work the same way when it comes to actually reading the voltage, though.

Comparison to Analog Models

One of the first things a digital device will do is convert the analog into a digital code proportionate to the magnitude of the signal. Voltages from picovolts to megavolts are measurable, though the scale usually graduates in millivolts, volts, or kilovolts. Frequencies between zero and several megahertz may also be measured.

Digital devices have a number of advantages when compared to their analog counterparts. The most obvious benefit is the ease of use when reading the digital display. Electric amplifiers and attenuators extend measurable ranges, and a digital model has superior resolution and a higher order of accuracy within plus or minus 0.5%. It also indicates a negative quantity when polarity is reversed. Analog meters are more fragile and tend to be more susceptible to damage.

Fixed Units

Many larger appliances actually have DVMs wired in, usually to their control panels. Many DVMs integrate outputs for monitoring, controlling, transmitting, and printing of data. Some of the most common laboratory and commercial applications include electromechanical machinery with a current flowing through wires and circuits, generators, and medical equipment like X-ray machines. In all of these cases the tool helps technicians quickly make sure that the equipment’s voltage is within the proper and safe range.

Advanced systems are often connected to computers, allowing for automation, optimization of processes, and prevention of malfunctions and critical failure safeties. Chemical plants can convert measurements to voltage and control and monitor temperature, pressure, level, or flow. Repair personnel and other operators can also use the read-outs diagnostically, often to identify problems before they become too serious.

Portable Options

Electricians and other electronics experts sometimes carry portable versions that can attach to larger appliances for a more on-the-go reading. Auto mechanics often also use specialized voltmeter devices to check car batteries.Portable or handheld devices, such as the digital multimeter (DMM), for example, may combine several functions into one instrument; many can measure not only voltage, but also current and resistance. These sorts of things are important to know before beginning any repairs or disassembling any devices, and can also be used to diagnose problems the same as a fixed voltmeter could.

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Discuss this Article

BookWhisk
Post 4

Tool shops often carry low-cost voltmeters that do a good-enough job for most applications. If you need accuracy and a robust meter, you are going to have to pay for a higher-quality device.

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