How to use a multimeter

Any home craftsman who has at least basic knowledge of electrical engineering should know how to use a multimeter (tester). Despite the fact that a modern device has a lot of functions, capabilities and measurement limits, it is quite simple. The main thing is to learn how to correctly connect the measuring probes, understand the meaning of all symbols printed on the front panel and be able to work with different ranges and modes depending on the situation. To understand the details of this issue, we suggest using the following instructions for using testers in practice. As an example, we will consider in this article a digital device, with which it will be much easier to work in comparison with a pointer multimeter. If you have not yet purchased your device, be sure to check out our DIY multimeter guide.

What is important to know about the device of the tester

Before starting any electrical measurements, it is worth understanding what the device itself is and what its functions are. All information is printed on the front panel. You can find out how to use a multimeter of the selected model based on the following generally accepted designations:

• ON / OFF - button for turning the device on / off (on some testers it may be absent, turning on the device in this case will be performed by turning the range switch);
• DCA (or A—) - direct current;
• ADCA - alternating current;
• ACV (V ~) / DCV (V—) - alternating / direct voltage;
• Ω - resistance.

To take readings, you need to use a rotary switch that allows you to set various modes of operation of the multimeter, select the measurement range.

One of the important points in mastering the question of how to use a digital multimeter is the correct connection of the test leads to the appropriate connectors. The correctness of the measurements will depend on this. In order not to be mistaken, there are simple rules:

COM - black size on the left, universal connector in the center, connector for measuring high currents - on the right

1. COM connector - common, it is used to connect a black negative measuring lead;
2. to connect a red positive probe, one of the sockets can be used to measure voltage (V), resistance (Ω), current (mA, A), while it should be borne in mind that, as a rule, there are two current sockets (for working with low-current circuits and with current up to 10/20 A depending on the tester model).

But it should also be borne in mind that when measuring voltage or current, the measuring probes installed oppositely will lead to a change in the polarity of the received data, which will be reflected on the display by the appearance of the “-” sign. The numerical values ​​will be correct in this case. This is how digital devices differ from analog ones. In the latter, the arrow most often goes beyond the scale, and in some cases such work can lead to damage to the device.

Instructions on how to use a multimeter for dummies

The main purpose of any tester is to measure electrical quantities. When measuring the current, the device connected to the circuit is connected to the open circuit (in series), and in order to use the tester as a voltmeter, it is connected to the circuit in parallel.

Using a DMM to Measure Voltage

The DC voltage measurement technique is quite simple.

1. Using the rotary switch, we select the type of the measured value and the measurement limit.
2. The setting of the limit can be done after the user has determined what the approximate value of the measured voltage is. A clue can be the markings on the batteries or parts of the electrical circuits. The limit must always be greater than the measured value in order to prevent overloading of the device elements and its failure.
3. In accordance with the operating manual, the test leads must be connected to the terminals / outputs (black - to "minus", red - to "plus").
4. We get the constant voltage value on the tester display.

we measure the voltage of the electrical network

Another way to determine the measurement limit is to initially set the connected device to the maximum measurement limit. Then, after taking readings, to improve the accuracy of the data obtained, you can reduce the limit to the nearest higher value, comparing it with the measured readings. There are no fundamental differences in how to take data on DC and AC voltage. The only difference is to switch the tester to the desired mode. Then the above algorithm works.

Practical example of using the voltage sensing function

check the voltage on the battery

One of the most common operations in which you need to measure voltage is checking the condition of the batteries. Moreover, it can be both ordinary finger and automobile. In any case, it will not be superfluous for a home craftsman to know how to use a multimeter correctly in such a situation. If we are talking about finger batteries, measurements are carried out as follows: the switch is set to the desired DC voltage limit. The resulting value should correspond to the nominal. A deviation of ± 10% from the nominal is considered normal.

How to measure current

Before using a tester (or multimeter) to measure the current strength, you need to determine whether the device under test works with alternating or direct current. In addition, you need to know the approximate value that will be obtained as a result. This will allow you to choose the correct mA or 10/20 A jack used for operation. Even if you have no idea about how much current you will get in the end, it is easy to solve the problem. It is enough to start with setting the maximum limit, and then, focusing on the data obtained, if necessary, re-measure the value by moving the measuring probe and switch to a smaller range.

Continuity of circuits with a multimeter

Continuity is one of the main modes that is often used in the home use of multimeters to detect open or short circuits in a circuit. It is enough just to set the desired mode on the tester, turn off the power (including such a low-power one as batteries), discharge the capacitors, install test leads and connect them to the desired points of the electrical circuit.

For the convenience of the user, in the absence of breaks, most models have a buzzer, the signal of which makes it easy to navigate the results. In addition, the display in this case will show the resistance value or "0". Absence of sound or display of "1" on the screen will mean an open circuit in the tested circuit. You can learn more about the continuity of wires, switches and other devices in this article.

Resistance measurement

A huge "plus" of the very operation of measuring resistance will be that when measuring it using a multimeter, it is almost impossible to spoil the device or part in the equipment being repaired. To perform the operation correctly, you need:

1. set the rotary switch to the Ω sector,
2. turn off the power, remove the batteries, battery,
3. choose the most suitable measurement limit,
4. connect to the terminals of the measured circuit element,
5. take readings.

measure the resistance of the incandescent lamp

The whole procedure is fairly standard. The only important difference is that after taking measurements, you may see “OVER”, “1” or “OL” on the display. This means that an overload has occurred and the measurements must be repeated, switching the device to a larger range. Also, the display may show "0", which means the need to lower the limits. To successfully use the resistance measurement function, knowledge of these simple rules will be sufficient.

Capacity measurement

Radio amateurs and electricians who repair household appliances often need to measure the capacitance of capacitors. This issue is no less relevant for machine tool owners who periodically need, when connecting a three-phase motor to a single-phase network, to select the capacity of capacitors to optimize the operation of the motor. These operations are performed by analogy with measuring resistance.

An important difference is not only in the position of the switch, which must be set to the appropriate mode and range, but also in the mandatory preliminary discharge of the capacitors. Otherwise, at least incorrect readings will be obtained (when working with small-capacity cells), as a maximum, the device will fail. As a rule, manufacturers provide separate sockets in the multimeter for operation in the capacitance measurement mode.

Detailed video instructions

In the first part of the video, you will find general information on how to use a multimeter and learn how to measure AC and DC voltage.

After reviewing the second part, you will learn how to measure resistance, ring circuits, test diodes, use the built-in generator, and also measure the amount of electric current.

Safety when working with a multimeter

There are several potentially hazardous situations in which ordinary carelessness by the user can lead to instrument breakdown and failure of the UUT.

1. If it is necessary to measure the voltage, while the probes are installed correctly, and the switch is in any position other than voltage (on resistance, current).
2. If current is to be measured, the test lead is installed in the low current socket, and the switch will be set to measure high current.
3. When dialing or measuring resistance in the equipment, it is necessary to remove all the batteries installed in it, since operating in this mode will disable the device.
4. When operating in continuous mode, if there are charged capacitors (capacitors) in the circuit, it is imperative to discharge them by short-circuiting. When operating circuits with high-capacity elements, discharge can be performed through an incandescent lamp. Failure to follow this rule may result in the multimeter burning out.

All of the above situations lead not only to material losses, but also to increased danger for the person working with the tester. If you use the multimeter incorrectly, working with electricity can lead to accidental contact with live parts that are under high voltage, and this is already dangerous to life. For the rest, it is enough to comply with simple rules and laws of electrical engineering in order to easily master working with a multimeter in all its modes and successfully carry out the necessary measurements without resorting to specialists.