Multimeter and their types

Multimeter
Multimeter

A multimeter, which combines three basic measuring instruments (a voltmeter, an ammeter, and an ohmmeter), allows you to measure voltage, amperage, and resistance. Used to test items such as batteries, radio components, cables, electrical circuit switches, power supplies, motors, etc. Electricians, workshop employees, laboratories, etc. use tools to diagnose and troubleshoot electrical systems.

Wide choice

Multimeters can be digital or analog and differ in the range of values ​​\u200b\u200bfor which they are calculated. The latter determines which devices can be tested with a specific model and which cannot.

Measuring tools can have special functions that make them more useful for certain tasks. For example, the best multimeters with an oscilloscope allow you to read the change of the measured parameter over time. The temperature sensor is useful when measuring temperature-sensitive components of a computer.

Buyers who consider the additional features of multimeters will surely find a model that meets their needs.

how to choose a multimeter

Basic measurements

Multimeters are used for measuring three main parameters of electrical circuits, components and systems are voltages, resistances, and currents.

In voltmeter mode, the device determines the potential difference, i.e. the voltage (constant or alternating) between two points of the electrical circuit. This is the most common type of electrical circuit measurement, which is achieved simply by touching the test leads to two different places in the system. The device determines the potential difference, without requiring changes in the circuit.

Like an ohmmeter, a multimeter measures the resistance that a particular element provides to electrical current. In this case, the part must be removed from the chain for individual testing. Attempting to measure the resistance of an item connected to a power source may damage the meter.

In addition, in the ohmmeter mode, a dial with a multimeter electrical circuit is also produced. Unclosed contours have infinite resistance, and closed – small. In the latter case, the device emits a sound or a light signal.

The ammeter measures amperage (constant or alternating) when the multimeter becomes part of an electrical circuit. That is, the measuring device itself must be included in the circuit, breaking it in such a way that current passes through it.

electrical multimeter

Digital or analogue?

One of the first decisions that should be made before choosing a multimeter is deciding between a digital model and an analog model. In addition, it is necessary to clarify a number of issues related to the power of the device and its intended use.

Digital multimeters differ from traditional analog ones in several ways, including the way they display indications, the level of accuracy, and the ability to download data to a computer. The measurement results are displayed on the LCD screen as specific decimal numeric values. Accuracy is generally considered to be within 1% for direct current and within 2% for alternating current. Digital multimeter readings can sometimes be downloaded to a computer for later viewing and analysis. And oscilloscope devices allow you to get a lot of data associated with the timeline.

The measurement result of analog multimeters is more difficult to count, since it is displayed by a pointer on a numerical scale with discrete values. The user must interpolate intermediate readings, so the accuracy of such measurements does not exceed 2.5%.

Multimeters for different purposes

The sensitivity range is the maximum and minimum value that the meter can read. In general, this determines the scope of each specific model. The characteristics of a multimeter designed for a car battery voltage are not sufficient to measure low voltage sources. This means that the buyer must know exactly the purpose of using the meter. For example, the most popular inspection objects are fuses, batteries, incandescent lamps, lighting switches, boilers, transistors, integrated circuits, automotive electronics.

Different applications require different sensitivity ranges. Low voltages in integrated circuits cannot be tested with a multimeter designed for testing automotive systems.

arrow multimeter

Resolution and numbers

Resolution is defined as the smallest change in the input signal that produces a change in the output. The resolution of the digital multimeter is expressed by the number of digits it can display. For example, a 3½-bit indicator consists of 3 digits, taking values ​​from 0 to 9, and a position with values ​​of 0 or 1. Therefore, the resolution is ±1999, because the device can display positive and negative numbers from 0 to 1999 Most instruments on the market are 3½ or 4½-bit with a value range of ±1999 or ±19999, respectively. Sometimes in the instructions for the resolution of the multimeter there is a number that the device can display without changing the measurement range. In this case, a 4½-bit display is indicated by a score of 19999 or 20000.

Multimeter types

Analog multimeter

An analogue multimeter is a type of multimeter that measures electrical quantities such as voltage, current, and resistance using a needle on a scale. When a quantity is measured by an analogue multimeter, the result is shown in analogue form, with a pointer indicating a specific scale value. The scale’s readout represents the quantity being measured. It is made up of a moving coil metre with a needle that displays the value on the scale.

Its main functioning idea is that the pointer deflects based on the force applied to it. It consists of a drum sandwiched between two permanent magnets, with a coil wrapped around it.
A magnetic field is created when a specific quantity of current is sent through the coil. Furthermore, a magnetic field exists as a result of the permanent magnet reacting with an induced magnetic field. As a result, the indicator affixed to the drum deflects as a result of the resulting force. This hand’s movement is regulated by springs that apply opposing force to its movement, resulting in a balanced deflection.

Definition of digital multimeter

Another sort of multimeter is a digital multimeter, which employs a digital display to portray the measured quantity in the form of digits.

The use of analogue multimeters has been somewhat curtailed with the advent of digital multimeters. This is primarily owing to the benefits associated with digital multimeters. The display unit, along with encoders, analogue to digital converters, signal conditioning circuits, and other components, is the major component of a digital multimeter. Assume we need to test the resistance provided by a specific resistor. As a result, current from a constant current source can flow through that resistor to accomplish this. The voltage across the resistor is amplified and fed into the ADC.

 

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