How does a multimeter work?

If we ask an electrician what instrument he uses most in his work, he will most likely answer “The multimeter”. Is that the multimeter is one of the most important devices in the electrical field due to the large number of functions that can be performed with it.

What is a multimeter?

A multimeter, also called a tester, is an electrical and portable device that allows a person to measure different electrical magnitudes that are part of a circuit, such as currents, powers, resistances, capacities, among others.

It can measure magnitudes in different ranges, that is, if we know that we are going to measure a current of 10 A (Amper), then we will choose a range from 1 A to 50 A. It can measure direct current or alternating current digitally or analogically .

What is a multimeter used for?

A multimeter has many functions. In general, it is used to measure different magnitudes in an electrical circuit . Some of the functions of the multimeter are:

  • Resistance measurement.
  • Continuity test.
  • Alternating Current and Direct Current voltage measurements.
  • Alternating and direct current intensity measurements.
  • Capacitance measurement.
  • Frequency measurement.
  • Detection of the presence of alternating current.

How does a multimeter work?

The operation of a multimeter involves various measuring instruments, such as the voltmeter, ammeter , among others. What is important to know about a multimeter is knowing how to use it.

In principle, we must identify what we are going to measure and have an idea of ​​what values ​​that measurement ranges between. Once identified, we look for the data on the tester scale. For example, if we want to measure the voltage of a direct current of 100 V, we look in the tester for the V that next to it has a continuous line and we choose the largest value, closest to the approximate measurement value.

Then the cables must be connected to the multimeter. The black cable must be connected to the plug labeled COM, for common. Then we look for the peg that has as denomination the magnitude that we want to measure. If we want to measure voltage, we look for V and connect the cable to that pin. Then the other terminals of the cables must be connected, the black in the negative part of the circuit and the red in the positive part of the circuit.

Then the multimeter, if it is digital, will show the value on the screen and if it is  analog, the needle will move to the measurement value. The following video explains how to use the multimeter in more detail.

Types of multimeter

There are two types of multimeters:

  • analog multimeter
  • Digital multimeter

Analog Multimeter 

Analog multimeters show the measurement result by means of a needle that indicates the measured value on a scale. They have an approximate voltage measurement accuracy of 1% and a range of 0.4 mV to 1000V. If we talk about current intensity, it can measure between 0.1 μA and 10A, with an accuracy of 2%.

Digital multimeter

Through a circuit, the digital multimeter converts the analog data obtained into digital values ​​that are then displayed on a screen. These types of multimeters measure with the same accuracy as the analog ones, but increase the precision when reading the measurement, since there is a small error with the needle.

How to use a multimeter

As we explained in the previous paragraphs, the multimeter has many uses. Among the most common uses are:

  • For voltage measurement
  • For resistance measurement
  • For intensity measurement

Stress measurement

To measure voltages , simply connect the cables to the multimeter and the other terminals between the points where you want to measure the potential or voltage difference . If we want to measure the absolute potential, we place the terminal of the black cable in any ground and the red one where we want to measure the potential.

 Resistance measurement

The process is similar to that of stress measurement. The multimeter scale should be placed where we find the Ω symbol and we look for the resistance value that most convinces us. Finally we place the terminals between the points where we want to measure the resistance.

 Intensity measurement

When it comes to measuring intensities, the process is a little more complicated. It is that the voltages and resistance are measured by putting the multimeter in parallel, but to measure currents the multimeter must be in series.

Therefore, to measure intensities , the circuit must be opened to place the terminal of the red cable in the part where the circuit was opened and the current circulates through the tester. Previously the tester must be configured to measure intensities.

Parts of a multimeter

A multimeter consists of the following parts:

  • Display: It is the screen that digitally shows the result of the measurement.
  • On/Off switch
  • VDC/VAC/OHM/ADC/AAC: scales to select depending on the measurement to be performed.
  • Selector: Wheel that allows you to select the scale for the measurement you want to perform.
  • COM: Socket to plug the black cable, regardless of the measurement to be made.
  • V-Ω: Socket where the red cable is plugged if you want to measure voltage or resistance
  • 10 mA: Socket where the red cable is plugged if you want to measure intensities of up to 10 mA
  • 10 A : Socket where the red cable is plugged in if currents of up to 10 A are to be measured.

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