# How to measure the voltage by a multimeter, how to check constant and alternating voltage

## All stress measurement nuances multimeter

Voltage, or voltage, is one of the electric current parameters showing the difference in potentials on the chain area. It is equivalent to the electromotive strength, and is actually one of the most important factors for the operation of any electrical appliances.

Voltage checking is almost the most common operation that has to be carried out in working with electrical engineering, regardless of whether the maintenance of this industrial or household (home) power grid.

From its magnitude, as well as from the very fact of availability, it depends whether the electrical appliance will work, and can it be out of order. Currently, the device called the multimeter is used to measure the voltage.

## General purpose

This is a multifunctional device designed to measure a number of electrical current parameters. Modern multimeter, even semi-professional, intended for household needs, is able to measure:

• variable and constant voltage;
• variable and constant current (current strength);
• resistance.

This is the minimum list of functions that even the simplest device possesses. More complex have function of diodes and transistors, cable integrity checks, etc. There are models that allow you to measure even the temperature.

The usual household appliance is used in networks, the voltage of which is not higher than 1000 volts permanent or 750 volts of alternating current. To measure high voltage, only a professional high-voltage multimeter applies.

## Device

We will consider digital multimeters (they are testers), since. Analog (equipped with an arrow and field with a scale of values) Currently, almost out of everybody.

There is a wide variety of multimeters on the market, but all of them have the following elements:

• digital display;
• Switch for setting parameters;
• 2-4 sockets for connecting contact probe;
• Two contacts probe.

Works device from the battery. We will consider the simplest multimeter for home use, measuring the three basic parameters - voltage, current strength and electrical conductor resistance.

The overwhelming majority of other functions are not needed in everyday life, with the exception of the transverse function. But before switching to the measurement of the voltage, we'll figure it out what it happens.

## The difference between variable and constant voltage

It will be more correct to talk about the difference between constant and alternating current. Various electrical appliances operate either from direct current or from alternating.

The variable means that the direction of movement of electrons in the conductor changes from the plus to minus at a given frequency, that is, the polarity of the current changes. In the household outlet according to the standard, the active voltage is 220 V, (amplitude 311 c) and the frequency of the current change of 50 Hz. This voltage employs all instruments included in the outlet.

But batteries and batteries are sources of DC. They always have a fixed plus and minus (polarity). The frequency in DC, naturally, is absent.

## Connecting plugs

Before measuring the voltage, the multimeter must be set to the appropriate mode. ACV abbreviations are used to marking the voltage - alternating, and DCV - constant or pictograms that complement the designation V - voltage. So, V ~ is an alternating voltage. V with a horizontal long line, under which three shorts are constant.

If your device is only the designation V, it means that it is able to automatically determine, alternating it or constant.

In addition to the icons denoting the type of voltage, the values ​​are applied to the multimeter housing. Most household appliances have measurement boundaries up to 750 V alternating and up to 1000 in constant voltage.

Before measuring the voltage in the outlet, on the battery or other instrument, connect to the cream multimeter. Their two are black and red. But the nests can be two, and three, and four - depending on the class of the device.

Black dipstick is either minus or "zero". It is always installed in the multimeter socket, indicated by COM. Red probe - either plus, or "phase". To connect it, the socket is selected, equipped with appropriate labeling. If the nests are only 2 - the question is removed, if more - choose something, about which there is a symbol of V.

Other sockets can be labeled either 10-20a, or Ma - respectively to measure the current force (ultra-large or supermala), or have other designations and, accordingly, destinations. The slot for the voltage is always one.

## Setting the measurement mode

After installing the probe, move the multimeter switch to the appropriate range. If the voltage is measured in the outlet, select the threshold value of 750 ACV, if, for example, a car battery - 20 or 200 DCV.

You must always set the measurement limit above the alleged voltage at the power source. Otherwise, you risk burn the device.

There is a rule: the voltage is measured by parallel connecting the multimeter, while the current is sequentially with the load). In practice, this means that in order to measure the tension in the outlet, you just need to insert both the multimeter probe into it, each in its nest. Where zero, where the phase does not matter.

The instrument shows the voltage in the volume it is adjusted. Thus, if you set the upper threshold at 750 V - you will see a value on the screen in the range of 210-230 V. or less, or more if the voltage jump is very large, but above 750 in it can not climb. But if you put the threshold in 200 V, then with the actual voltage value above this boundary, a number 1 appears on the screen.

Note that exactly 220V in the household outlet is not always available. Permissible deviations plus-minus 10-15 V.

Checking the three-phase line is carried out by the contact of two multimeter probe with two tires. Between them should be 380 V, between one bus and the earth will be 220 V (plus-minus 15).

## Check batteries

How to measure the voltage on the battery?

It is necessary to edit a black probe with its minus, red - with a plus, and set the border to 20 DCV. For any domestic batteries and batteries, this is enough. For comparison: a passenger car battery gives 13-14 V. Only powerful truck batteries are designed for voltage 24 V and above.

Multimeter will show the preserved battery charge. If you confused polarity - nothing terrible, just on the screen will appear "-". Checking the battery, keep in mind that the "fresh" battery must issue a slightly larger than indicated on its package.

Cressing the probe to the battery or battery contacts, you should not be afraid of the shock: the threshold of human skin sensitivity is 36 V. Even 20 in you will not feel. But checking the current in the opened electrical appliance or outlet, you need to be careful. You can not use probe with damaged insulation.

## Possible malfunctions

If the multimeter stopped measuring the voltage or incorrectly shows it, check the battery placed inside the case with another tester, or simply replace it.

Check also, whether the exposed voltage measurement threshold corresponds to the object you check. Check if the character of the voltage is true - the battery is not checked in the variable mode, but the socket is a constant voltage.

If the parameter is not defined in one socket, check it into another. If the problem arose when checking a small battery, it is possible in poor contact of the probe and terminals.

Test the device on various objects, a priori workable. If the multimeter in principle stopped measuring the voltage, then either the built-in current source is dried, or the control board is damaged, or the most frequent case is damaged by a cable of one of the probe.

You should examine cables for a break, make sure in good contact with the socket. If the rupture is detected - replace or replace the wire, restoring its integrity.

If no visible causes of working capacity is found, then most likely the multimeter burned down . This could happen due to trying to measure the overestimated voltage or a powerful network jump or other reasons.

## How the multimeter is arranged

As it is clear from the title, the multimeter serves to measure several electrical values. The multifunctional device combines a voltmeter, an ammeter, an ohmmeter, a call, and can also have additional functions like a thermocouple or low-frequency generator, testing capacitors and transistors.

Analog testers with a scale and arrow are almost never found, as it has long been ousted by available digital devices. The latter, in addition to the accuracy and number of modes, differ in the type of definition of values. Automatic show the result immediately after selecting the mode, you need to additionally set the measurement range in the manual.

All multimeters have a similar design. A screen is located on the front panel, there is a swivel mode switch below it, and slightly below - connectors for connecting probe. Some models have buttons to turn on the backlight, memorizing readings and for other additional functions.

Wires with affairs that need to touch the part during measurement are connected to the appropriate connectors. The black wire is always to the nest with the designation COM, and the red - depending on the value of the current. If it does not exceed 200 mA, then to the VΩma connector, if exceeds, then to 10ADC (10a max). In everyday life, such high currents are not found, therefore the VΩma jack is mainly used.

The numbers on the scale indicate the maximum value that can be checked in this range. For example, in DCV 20 mode, a constant voltage is measured from 0 to 20 V. If it is 21 B, then you need to switch to one step above, to position 200. It is important to choose a range according to the measured, otherwise the multimeter will deteriorate.

## How to measure constant voltage multimeter

Make sure the probe is correct.

Switch to constant voltage mode. It is usually denoted by symbols V with a straight and dotted line or DCV.

In multimeters with a manual range of ranges, additionally set the approximate measurement value, and it is better to step above. If you are not sure, start with the maximum and gradually lower.

Touch the contacts of the contacts and look at the screen. If a minus sign is displayed with the digit, then the polarity is confused: the red probe applies to the minus, and the black plus.

In the manual multimeter, it may have to be used to adjust the measurement range.

If the display is on the display, you need to increase the measurement limit, if zero, OL or OVER characters - downgrade.

## How to measure variable voltage multimeter

Check that the probes are connected correctly.

Turn on alternating voltage mode. It is marked with symbols V ~ or ACV.

In manual multimeters, also set the approximate measurement value. Better one step higher or the most maximum.

Apply the probe to the contacts and read the testimony from the display.

If a multimeter with a manual definition of bands and on the screen, the unit will increase the measurement limit if zero (OL, OVER) - lower.

## How to measure the resistance to the multimeter

Make sure the probe is correct.

Put the resistance measurement mode. It is indicated by the symbol Ω.

If the tester is manual, select an approximate measurement range.

Touch your resistor to the conclusions and look at the screen of its resistance.

On the manual multimeter, if necessary, adjust the measurement range in a large or smaller side.

## How to check the diode or chain multimeter

Insert the probe into the correct multimeter connectors.

Switch to diode ring mode marked with an arrow with a vertical line.

Apply the needles of the probe to the conclusions of the diode. The multimeter will show the voltage drop on the screen. If you change the probe in places, then when the work diode will be the unit, and on the faulty - any other number.

In the same mode, you can ring the chain or wire, but you must pre-de-energize them. If the integrity is not violated, the beep sounds, if there is a break - the unit, OL or OVER on the screen simply appears.

On some multimeters, the sound mode is turned on separately. For example, on a black tester, as in the photo above. This mode is indicated by an increase in volume, nota or speaker.

## How to measure current current multimeter

Connect the probe to the desired multimeter connectors depending on the current value.

Set the current measurement mode (DCA, MA).

In a multimeter with a manual range of ranges, set the maximum threshold.

Connect the probe to the chain sequentially. In contrast to voltage and resistance, the current is measured not in parallel. That is, it is necessary not to simply touch the two points of the circuit or the outputs of the part, but connect the multimeter into the chain rupture. With parallel inclusion, the device may fail!

Current consumed on the screen. If the multimeter is manual, then you may have to switch the range for more accurate results.

## How to check the voltage multimeter?

Multimeter - a device that combines an ohmmeter, voltmeter, an ammeter, stand for checking diodes and transistors, current frequency meter in the chain, capacitance capacitors and even air temperature in the room. Along with an ohmmeter and an ammeter, a voltmeter is considered to be particularly popular - a multimeter, working as a voltage meter in ethernets and electrical panels.

## Legend on the device

You can check the voltage by a multimeter by switching the latter to the measurement mode of constant or alternating voltage. Next to the highest range of measuring constant and alternating voltage indicates a zipper icon with an arrow at the end - An identification symbol, indicative of voltage, life-threatening.

Dangerous in most cases is the variable (with a frequency of 50 hertz) voltage up to 41 volts, as well as constant to 110 V. If you wash your hands, then any voltage is considered to be dangerous above 12 V.

The higher the frequency, the lower the limit: Experienced masters noted cases when even sound frequency voltage up to 40 V, supplied from the amplifier to any of the speakers in hundreds of watts, beat the current. For example, cases of shocks with a voltage of 20 V with a frequency of 8 kHz are noted. Believe carefully to work under a voltage of several dozen or hundreds of volts: Random touch of a current-carrying part can be for unprotected novice fatal.

The following icons are also not deprived of meaning:

• Icons "V ~" and "A ~" mean respectively variable voltage and ampero;
• HFE - the gain gain of the transistors (in reference books as H21);
• Icon of the dynamics or "squeezing" - the ring mode (resistance up to 200 ohms, at 50 orals is triggered);
• Diode icon - checking diodes and transistors without the need for their withdrawal from the board;
• K - Kilo prefix (kiloma);
• M - "Mega" (megaoms);
• M - "Milli" (most often it is milliamps);
• The lowercase Greek letter "MJ" is the "Micro" prefix (microampers);
• Capital Greek "Omega" - resistance in Omah;
• F - Faradays (capacitance capacitors);
• Hz - Hertz (current frequency);
• Degree icon or chamber "Temp." - air temperature measurements;
• DC - from the English. "DIRECT CURRENT", DC Parameters;
• AC - from English. ALTERNATING CURRENT, AC Parameters.

The last two markers sometimes replace the dash icon (permanent current) and "Tilda" (variable) respectively. It is recommended to remember them - at least those responsible for measuring the current, voltage and resistance. Others require special knowledge.

## Description of the verification process

It does not matter which voltage you decide to measure - PC power supply, variable wire voltage in the electrical tailor or terminal box. The process in all cases is similar to: if you do not know or are not sure which voltage value is present on current contacts, always expose the highest limit.

### On the battery or battery

Understand how good the battery can, only measuring its tension. Switch the multimeter to the "2000 Milvololt" mode - or on "20 volts" if the battery, say, is not calculated by 1.5 V, and by 9. The measurement range must contain the "DCV" marker (constant voltage). By connecting the red to "+", and black - to the "-" conclusion, you will get a value, for example, 1.459 V, or 8.75, depending on the battery you use for certain purposes.

If you confuse polarity - the tester will show exactly the same tension, but with a minus.

Batteries of different electrochemical systems have different tension. So, nickel-metal hydride (size with a normal battery) is characterized by a voltage of 1.2 V, but it can reach 1.5 in the full charge mode. Assembly of nickel batteries used in screw leads have a voltage of 12, 14.4, 18 and 24 V (respectively, 10, 12, 15 and 20 batteries connected in series).

Lead-acid "banks" from the car battery give 2.1 V, ready-made assemblies (6 elements), installed in the alarm security and fire devices - 12.6 V (can reach 13.65 in the full charge mode).

Batteries from tablets, smartphones and ultrabooks - 3.7 V (up to 4.2) per element, including the elements of the 18650 sizes used in laptops and screwdrivers. It is possible to estimate their fitness and the ability to take a charge by referring to the data on the minimum allowable voltage, below which they irreversibly lose the working capacity.

### In the outlet or on the windings of the transformer

The source of alternating voltage is both a socket (without any secondary voltage sources) and the conclusions of the secondary windings and transformer taps, the conclusions and terminals of the frequency converters operating from DC. As the latter, the frequency converter facing after the network rectifier. This is one of the main functional "Charging" function for smartphone, tablet or laptop - element of a pulse power supply.

Move the tester to the alternating current measurement mode with a voltage of 750 V. The measurement range is marked with the "ACV" marker. Insert the probes into the socket (or extension). Nominal - 220 V, but the tolerance is 10% (198-242 V).

The specific value depends on the loading of the transformer substation and the length of the line of the phase, on which the "sits" is your apartment or house. For example, the tester can show 234 V.

If you have a downstream transformer, which indicates the secondary winding voltage of 22 V, then with a network voltage to all the same 234 in it can give it, for example, 23.4 V. But from the frequency converter, it will not be possible to remove accurate readings. The fact is that In the tester, conventional rectifying diodes are applied, calculated on the frequency of everything in dozens of hertz .

If you measure fast voltage, say, 30 kHz, with which most pulse power sources work, the testimony will change chaotically. Every second, the tester will show, for example, 17 V, 74 V, 195 V, 310 V (large values ​​are the voltage of the half-wave), as a result, not exceeding several hundred volts.

The shown voltage changes wave-like, unpredictably - from tens to hundreds of volts. To display the correct value (stabilization of indications), a diode with a higher boundary frequency (for example, 100 kHz) is included in the gap of the measuring circuit.

## Possible problems

No device, including a digital multimeter, is not deprived of the ability to display incorrect or incomplete data or not to display them at all.

### Do not turn on

If the tester does not show anything - check if it is enabled at all. Next, check if there is a battery in it, did it not be discharged so that he stopped turning on. Check if the display is configured. If the tester is turned on, but with a new battery, it does not show anything - the reasons are as follows:

• Wire a power or terminal, the battery is damaged or its contents flowed;
• The device fell, hit, got intoxical, caught the display lost contact with the interface module (digital matrix controller);
• In case of aggressive chemicals, liquid crystals have flowed and the reflective film is damaged - the screen becomes not just not working, but white;
• Faulty central microcircuit controlling the operation of the device.

If you have the necessary knowledge and repair skills, you can disassemble the device. Find out that it is defective in it, you are fine forces. In the latter case, when the ADC does not work (microchip with the converter), the multimeter will not be able to repair. An exception is only the situation when there is another multimeter at hand, in which the screen, buttons and / or switch are damaged.

### Exaggerates voltage values

If the battery is discharged - the device will start "lie". There were cases when the "rosette" voltage instead of 220-240 in shown, for example, 260-310. This happens when the battery is discharged to 7-8 volts. Replace the battery to the new and repeat the measurements in the same place. Most likely, this problem will be solved.

### Display too "pale" or "bright"

Lightly highlighting all sectors of numbers on the background of the necessary (for example, figure 8 on the background of the figures 3) - the indicator that you got a battery with a voltage, randomly produced above 9 in, for example, 10.2). Also, this is observed when the tester is forcibly powered from a power outlet from a 12-volt power adapter, which is an exception. Do not apply power with a voltage than 9 V.

The pale glow sectors of the display (barely visible numbers) indicates that the battery is discharged to 6 V, the multimeter is about to turn off. Change the battery.

### Incorrect digit display

For example, if you saw instead of the "8" title "L", "bar", "gap", "minus", title or lowercase "P" (or "u", "C", "A", "E" ), "Soft sign" (all this should not be), then the display controller failed. In some cases, the corresponding digital matrix elements may be partially damaged.

If you have a good matrix from the exact same tester in which the "motherboard" burned or crashed - you can rearrange the surviving display from it, and then compare the results. If the same problem is detected, the suspicion already falls on the display controller. Here you will not do anything. Purchase a new multimeter.

### Does not work "Cook" in transversal mode

On some multimeters there is a button that turns off the squeak of the device when the line is called. Make sure the alarm is not turned off. Otherwise, the fee of the "Food" was disconnected from the board or it was scolded or damaged in the past inactive repair of the device. Install the sound empty from the other of the same tester. You can work without it.

### Highlight does not work

If you did not turn off the backlight using a special button or the battery does not "sat down," the sign of the non-working backlight may be defective or disciplied LEDs. Check out (and replace) them. You can work without backlight.

In any case, if there is no confidence that you restore the device, then refer to the master specializing in the control and measuring equipment.

### Inhibited operation of the device

Slow multimeter response to the change of conditions, for example, Connecting other resistors, indicates defective auxiliary parts on its board . So, if the resistance does not change immediately when adding a resistor, in standby mode, the last digit "0" changes to "1" and back, then the reason for the malfunction of the capacitors on the instrument board.

### The screen turns on and goes out

When the screen lights up at startup, but in a few seconds, after switching on, it goes out - the problem in the master multimeter generator. Because ZG is part of the main chip, you are unlikely to achieve something here, this item is not subject to replacement. The replacement is subject to the entire device.

## Safety regulations

Multimeter is safe to use. It has affects protected from user defeat with electric shock, even when the device or electrical installation is under high voltage. The probes are guaranteed to withstand the voltage of 220 and 380 V, with which the consumer faces often, daily. But this does not mean that there is still no more security rules.

1. Do not measure high short circuit currents exceeding 20 A. This may cause an overheating of the shunt. Comable case: the outlet is not measured voltage, and the power of the current is without a consumer. The fact is that the ammeter is turned on consistently, and not in parallel - you can burn the tester, get a short circuit. Perhaps there will be skin burns from the melted wire and / or probe. The same applies to the resistance measurement mode - may explode and pour the battery: it is not calculated for alternating voltage, 25 times higher than it.
2. If the voltage, the current or resistance of the chain is unknown, turn on the largest limit from those that refer to the measurable parameter or its nominal. For example, for a 12-volt block, at least a range in 20 V.
3. When the voltage is less than 750 B, the likelihood of damage to the instrument is high. The same refers to the hopping changes of amplitude - for example, with strong interference, the sudden carving of static electricity (high electrification of rubbing things and objects).
4. Working under high voltage, use dielectric gloves.
5. Measuring current strength Over 10 A, take breaks for a few minutes. The shunt is essentially, this conductor with a diameter of 1.5 mm - overheats for 10-20 seconds. The fuse at the entrance "10 A" is missing.
6. Do not replace the battery while the device is turned on and connected to the chain. De-in him.

Under the observance of the above requirements, the device will serve you well and trouble-freely for many years.

Further, see the video with tips, how to properly check the voltage using the multimeter.

Multimeter is a device for measuring constant voltage, alternating voltage, constant strength of current, resistance, as well as for dough diodes, transistors and transversals. So, let's start learning to use the multimeter and the first thing you need to do is to attach the wires with the shoes at the end.

Black wire always join Som's nest:

With the red wire you need to be careful, because the nest " 10Adc. "- Used only to measure DC to 10 amps.

Nest " VΩma. "It has more opportunities, it is using it that you will measure resistance, alternating and constant voltage, constant current up to 200 milliamper, as well as nickname wires to short circuit.

It is very important to remember the difference between these two connectors so as not to spoil your multimeter!

## Symbols symbols on multimeter

1. Dance voltage measurement scale.
2. Scale for measuring alternating voltage.
3. DC measurement scale from 2 to 200 milliam.
4. Position for measuring DC up to 10 amp without a fuse - a nest is used " 10Adc. ".
5. Position for transistor transistors.
6. Sorption position for short circuit.
7. Scale for measuring resistance.
8. Position for diodes dough.
9. Hold button Need to fix the data obtained on the display. This is done to have time to write the results of measurements and do not keep numbers in your head, which are often confused and forgotten.

FFF - The device is turned off.

## We use a multimeter in practice

### We measure alternating voltage

We will measure the voltage in the outlet. To do this, we translate the switch on the variable voltage measurement scale and put on a 600 volt mark.

Next, carefully insert the probe into the socket and see the testimony. For this action, there is no special sequence, you can insert a red probe on the left, and the black on the right and vice versa.

You ask, why 600 volts, if in a rosette of only 220 volts? This is done for the accuracy of measurement, for example, we assume that in the outlet 220 volts, but in fact your management company or power supply supplying electricity into your home does not cope and cannot give you a stable 220 volt.

When measuring 600 volts, the display will show a value of less than 200 volts. If this happens, you should translate a 200 volt switch and then the device will show more accurate data.

As you can notice in the photo below, my electricity providers are perfectly coping with their responsibilities.

### We measure constant voltage

We measure the voltage that gives the battery. To do this, set the switch to this position (see Figure below):

Next, connect the red wire to the plus of the battery, and black to minus and remove the testimony. You can use the HOLD button to secure the result.

It turned out a value of 0.12 - it tells us that the battery voltage is less than we put on the scale of the multimeter. Without hesitation, we translate the switch to the value below and get the right and clear indications.

### Short circuit

Let's determine the integrity of the extension.

The switch is set to the call position, like this:

Touch the red dipstick to one of the contacts of the fork, and the black shock in the extension socket.

If a sound signal is heard, then it tells us that the extension core lived, starting to contact the plug to the socket connector - a whole.

Further, in the same way check the second contact of the fork and the hole of the socket.

Suppose you checked one core and a beep sounded, and when checking the second core, there is no sound signal. This means that in the second living, the breakdown and such an extension will not work.

With this multimeter function, you can ring any extension cable, wire, cable, live with any number. Before using the transvers, make sure that there is no voltage on the wire!

### Measuring resistance

We translate the switch on the scales for measuring the resistance.

Select the necessary installation on the scale of resistance.

1. 200 = 200 Ohm.
2. Check diodes.
3. 20k = 20 kiloma.
4. 200k = 200 kiloma.
5. 2M = 2 million Ohm or 2 megaoms.

Before measuring the resistance, make sure that there is no voltage!

### Test diode.

We set to the appropriate position (position 2 cm. Figure above) The switch arrow and closing the red probe on the anode (+), and the black probe at the diode cathode (-). The instrument display will show the resistance value. Next, we change the probe in places - the device must issue a unit on the screen. If in both cases the multimeter gives the number 1, then this diode burned down. The value is smaller than the unit - the diode is broken.

## Conclusion

So we learned the main features of the multimeter. After examining the instructions that are written above, you can figure it out with almost any electronic multimeter.

Multimeter - a combined tester, with which the parameters of the electrical circuit and its components are measured. The device is used not only in the professional sphere, but also in everyday life. Working with the device is quite easy. Those who are still new to electrical engineering, we suggest learn from our article, how to use a multimeter.

## Classification

The devices are classified into 2 groups - analog and digital. They differ in a set of functions, measurement accuracy, resistance to interference, ease of use. With the help of the tester, you can find:

• strength and voltage;
• resistance of chains and individual elements;
• capacitance capacitors;
• inductance coils;
• Temperature.

For the repair of electronic or digital technology, multimeters are simply indispensable. The devices help quickly detect the breakdown and fix it.

### Analog

There are arrogant testers consisting of a sensitive magnetoelectric meter, additional resistors and shunts. Information is transmitted to the graduated scale using a moving arrow. Advantages of analog devices:

• resistance to interference;
• sensitivity to changes in the electrical circuit;
• affordable price.

• large measurement error;
• nonlinear scale for which the preliminary removal of zero is required by a special regulator;
• low internal resistance;
• There is no automatic polarity determination;
• Unable to measure alternating current or voltage.

Nevertheless, some engineers prefer an analog version for cases when when testing electrical components, it is necessary to accurately determine the direction and trend of changes in the value.

### Digital

The tools of the latest generation are very popular in the mode of electronics, thanks to the ability to quickly and accurately measure the necessary parameters. Electronic multimeters are more adapted for everyday work, so they can confidently recommend novice. The form and dimensions of the device may be different, but algorithms for measuring the main values ​​are equally equally in all models.

Pluses of digital testers:

• The information is displayed on the display in the form of a number with one / two decimal places in the necessary units, which allows not to spend time on decoding;
• When replacing polarity, the values ​​are displayed with a minus sign;
• high internal resistance, which reduces errors to a minimum;
• Thoughtful interface and simple management helps to quickly master the measurement principles and proceed to work.

Minuses few:

• sensitivity to interference;
• Distilized display and distortion of values ​​when the battery is discharged.

Digital multimeters have an output for connecting a computer, which is recorded and further processing results.

## Design

Multimeters most often called digital testers. They can be both portable and stationary for professional use. The most convenient for home use is compact mobile models that can be kept in your hand. Outwardly, they are small devices in the form of a flat box. Power is provided from batteries. On the front surface there is a display, a disk switch for setting the mode and changing the range, 3-4 connector for probe and 1 for transistors.

The display shows the value of the measured characteristic. Using the control knob, the mode is set (measurement of current, voltage, resistance, etc.). In the circle, the indicators and their range are applied. When installing the switch, the label or arrow must be addressed to the desired sector.

Connectors serve to connect probe. Black wire for the rules adopted in electrical engineering always "minus". "Plus" can be any color, in multimeters, it is usually red. To measure the temperature in the kit turns on the thermocouple. Nests have designations:

• COM - "Earth", zero terminal, is intended for black probe;
• VΩma - to measure voltage, resistance and current to 200 mA, red probe;
• 10ADC - for current by force to 10 A.

The last two are used as contacts for thermocouples. Separately there is a connector for checking transistors.

Instruments can be produced in shock-dust-protected design. From mechanical damage, the electronic filling of protects the rubberized casing, and the hermetic case is made of non-combustible plastic.

## Bigness, Permission, Error

The bit of multimeter is a value that determines the number of discharges to record the measured characteristics. It defines the accuracy of the device, but the view (length) of the number. For example, the compartios 4 1/2 means that the display displays 4 full discharge and 1 half, that is, up to 19999 samples. If the value goes beyond these limits, you need to switch to another range.

The resolution denotes the degree of accuracy of the device, that is, at what interval it is possible to change the change in the characteristic. If the multimeter resolution is 1 mV in the range of 4 V, then when measuring the voltage in the range of 1, the difference between adjacent values ​​will be at least 1 mV.

The error of the digital multimeter is the highest error that is allowed by the device when measuring values ​​under specific operating conditions. What it is less, the closer the result is the result to the actual value.

Most often, the error is expressed as a percentage. For example, if it is 1%, then when the voltage is displayed in 200, a true value is distributed ranging from 198 to 202 V.

## How to set the right mode

If the switch is incorrectly installed, the device may fail, repair will be required. The first action that needs to be done before the measurement is to determine which current proceeds through the wires. Permanent current in batteries, batteries or power supplies, variable - in household power grid. If the character of the current is initially unknown, you can use the indicator screwdriver:

• If the indicator does not burn on any contact, there is a constant current;
• With alternating current, the glow in the screwdriver appears on the phase, there is no on zero.

Second - you need to choose a part of the sector for the desired characteristic. Standard notation:

• ACV or V ~ - voltage of alternating current;
• DCV or V - - DC voltage;
• DCA - DC strength;
• Ω - resistance;
• HFE - reinforcement of the transistor;
• The "Diode" sign is the mode of checking diodes.

The next step is to set the measurement range. When the current is unknown, the switch is fixed at the maximum value. If the current is more expected, it will help avoid breakage. So for the standard AC voltage of 220 V, the limit is set 600 or 750 V.

## How to use the multimeter: instruction for teapots

Consider how to measure several electrical characteristics.

### Potential

Algorithm for voltage determining:

1. Set the mode to the ACV or DCV position in the estimated interval.
2. Black wire connect to Som Connector, red to the VΩma connector.
3. Property tips connect with chain contacts. For example, enter the outlet or on the poles of the battery.
4. Measure.

The number that is displayed on the display is the voltage voltage. The "minus" sign suggests that the polarity was broken. If the multimeter supports the deduction function, the value can be fixed with the HOLD button. It is convenient for a large chain of measurements.

### Tok Power

This characteristic is measured only when the tester is serially connected to the circuit and power on. Most devices make it possible to determine the current strength up to 10 A, since in everyday life, large values ​​are rarely used. For measurements in the chain, a gap is arranged. Next steps in the following scheme:

1. Black dipstick - in the Som nest.
2. Red - into the connector up to 200 mA or 10a.
3. Tips carefully touch the contacts.
4. Read the voltage value from the display.

When working with bare wires, it is necessary to comply with the safety equipment to prevent the shock.

### Resistance

This characteristic can be measured without power supply. The element under study simply closes between two suphers. If there is no conductivity, the unit is displayed on the screen. Sequencing:

1. Set the mode Ω by selecting the maximum range.
2. Properties insert into the appropriate connectors.
3. Check the condition - close the probe on each other. A 0 or small number should appear, which must be taken into account when measuring the chain resistance.
4. End of the conductors to sample the objects of the object under study.
5. The screen will appear the resistance of the element or section of the chain.

For accurate measurements, it is recommended to spend 2-3 attempts.

### Measuring transistors

To verify the health of PN transitions and determine the gain:

1. Set mode
2. Insert the flows of the transistor into the connector in accordance with the basement, observing the PNP and NPN zones.
3. The display will be displayed the signal gain.

Diodes and the simplest transistors are also measured with the "diode" mode. A red probe (plus) is connected to the database, on the emitter or manifold black (minus). With the correct polarity, the transmission coefficient will be displayed on the screen.

### Capacity condenser

Before measurements, the capacitor must be discharged. It is possible to reset it with a screwdriver with an insulated handle, connecting the conclusions with each other, but more securely with a 15 volt light bulb with soldered affairs. Even a powerful capacitor up to 400 B is discharged quickly as without risk for the person and the electrical element itself. The measurement of the container is made according to the scheme:

1. Set FCX mode.
2. To connect the condenser to connect the red probe, black - to som.
3. Measure the container. On the display it will appear in the Farades.

With the condenser malfunctions, the resistance is infinite. The breakdown is characterized by a decrease in its multiple value.

### Svetonka

To establish the integrity of the wiring or cables, they are "transk". It consists in checking the resistance of the site at the minimum range of measurements:

1. Set the ring mode (icon "Sound mixer").
2. Connect the probe to the corresponding jacks, and the tips are to the ends of the wiring section.

If the integrity is not broken, the sound zoom will be heard, and the display will be close to 0. If the number is unstable and "jumping", conductivity is absent.

### Temperature measurement

Some models support temperature determination feature. For this, devices are equipped with thermocouples - conductor from different metals. When contacting the temperature medium, electric potential is formed between their ends. Measuring it, you can find the temperature of the object. On the scale with the thermal sensor function, the Temmer sector is provided, where the mode switch must be installed.

Measurement sequence:

1. Insert the ends of the thermocouple in the appropriate connectors, observing the polarity.
2. Apply the conditional spike to the point in which you need to find the temperature.
3. The screen displays the desired value.

If the polarity is broken, then when studying a more hot object, the temperature will decrease. To test the performance, you can clamp the end of the thermocouple in your hands. The screen should appear about 36 °.

## Popular models: brief overview of multimeters

Most testers are made in China. They definitely determine the electrical characteristics and, subject to the rules of operation, reliable and durable. It is important to know how to use a multimeter for beginners so that there are no problems when working.

### Multimeter DT830B.

Designed to measure the current not higher than 10 A. on the body 3 of the standard connector and one to check the transistors and diodes. The device is powered by the Croon Size Battery. For it there is no separate jack on the housing, it is inserted into with a completely removed back cover.

Complete 2 probe. One black, which connects to the SOM connector, the other red - in the second or third according to the measured value. Properties are made in budgetary execution. If desired, you can buy better, but these are quite convenient for use.

When measuring, the black wire is first connected, then red. Keep the probe need carefully, without touching metal tips. If the "plus" and "minus" are confused, the device will give this to know the sign "-" before the number on the screen.

The maximum voltage value for this multimeter - 500 V. When approaching it, the HV icon appears on the display, the High Voltage warning about high voltage. If the maximum measurement accuracy is needed, it is necessary to take into account the resistance of the probes themselves. This is determined by closing the tips to each other. Model DT830B inexpensive. The kit may not include instructions in Russian.

When using the tester, it is necessary to take into account features:

• The error is about 1%;
• manual installation modes;
• Execution is not a shockproof, plastic case when hit can be damaged;
• medium quality probes;
• No display backlight.

### Multimeter DT832.

The model is very similar to the previous one, but the functionality is expanded by the possibility of using the generator and temperature measurement. In addition to the probe, the thermocouple is included. For the convenience of users, the power indicator shows the batteries discharge, the WAT sign appears on the display. The protection system contains fuses that are burnd out when operator error, and then they must be changed to similar new ones.

To use the generator, the functions switch must be set to _ | ¯ | _ | ¯. Properties to zero and vωma. There will be a current of 50 Hz and a voltage of about 5 V between them, which can be used for its purposes.

### Multimeter DT838.

The model in appearance and the principle of operation is very similar to the previous one. Performs functions - measurement of parameters of direct and alternating current, transistors, transversal plus diode testing, temperature determination, capacitors. The generator is not in DT832. Properties are quite powerful and have great resistance. Included there is a thermocouple with a sensor. The design of the device is more clear, bright scale, major designations. Two-color switch, with a light arrow on a pointer. This allows you to make less wrong when rearranging modes. When overloading, "1" is displayed on the display. To protect from operator errors, the fuse is built into the system.

### Multimeter DT9208A.

The model has a wide functionality. With it, you can:

• measure current, voltage, frequency and resistance;
• call a chain;
• hold a diode test;
• Determine the transistor transmission coefficient and capacitor capacitance.

The device is equipped with a thermocouple, which is used to measure temperature from -40 to 1000 ° C. Battery discharge indicator - sign on the display + - - indicate that it is time to replace the power supply. During a pause, more than 15 minutes work automatically disabling the instrument. To enable it, you must click on the POWER button.

Feature DT 9208A - the ability to measure currents over 10 A. For this, there is a separate connector on the housing. For ease of reading data, the display can be rotated and installed at the desired angle.

All limits are protected from overloads with a combined system. The information on the screen is held using the HOLD button. To protect against chemical exposure and dust, the equipment may include a silicone casing. If it is not, it is recommended to purchase yourself.

### Multimeter DT9205A.

A high-precision device with an error is not more than 0.5% applied in field or laboratory conditions, workshops, households. Range of operating temperatures - 0 ... 40 ° C. Store is recommended at -10 ... + 50 ° C. The hull is quite large - 186x86x41 mm, made of durable plastic of yellow. The display is also large, all the numbers and badges read well.

Power is included with the POWER button. At the bottom there are 4 connector, including for measuring the current over 20 A. The connector for transistors - in the upper right corner. No functions for determining the temperature and frequency, using the generator.

### Multimeter DT-61

This device combines 6 functions:

• standard digital tester;
• moisture meter;
• thermometer;
• contactless alternating current meter;
• luxmeter;
• Noiseomer.

DT-61 is designed for professional and household spheres. The digital multimeter measures the strength and voltage of the constant / alternating current, the resistance, performs a transvelon of electrical circuits, testing diodes and determining the temperature. In addition, its functionality includes measuring the noise level in production shops, schools, offices, residential buildings, airports. The device checks the acoustics of studios, student audiences and equipment working with the allocation of noise pollution. To go to the noisener mode, the switch must be installed in the DCB sector, send the microphone to the sound source (horizontally). With strong wind, it is recommended to apply windproof.

The luxmeter function is used when determining the illumination of the rooms. The photosensitive selenium photocell converts the energy of light into electrical and determines the intensity of obliquely incident rays with high accuracy. To perform measurements, the switch is set to LUX mode.

The determination of air humidity is performed in ON mode. It is necessary to place the device indoors at least 2 hours. Indicators will be displayed on the display% RH.

## Conclusion

How to enjoy a multimeter - an urgent question for those who begin to step by step to master the basics of electrical engineering. The device will help determine the parameters of electrical circuits with great accuracy and speed. Some models perform the functions of a moistureometer, a luximeter and a noiseomer, which significantly expands the capabilities of these convenient devices.

The multimeter is also often called the "multi-meter", because it is designed to withdraw a fairly wide spectrum of indicators: Measurement of direct and alternating voltage, resistance and current forces. Many multimeters are also given the possibility of measuring the gain of transistors and provides a special mode for testing diodes, a circuit ring for a short circuit, etc. In a word - "Multi" (for a lot) "Tester".

The expensive models of such measuring devices include and additional functions: measurement of temperature (using a thermocouple probe), inductance of coils, capacitance of capacitors.

We will learn to use the multimeter on the example of the budget device of Chinese production worth 10-15 dollars "XL830L", as I use.

The set of deliveries includes a set of simple "probe" (red and black wires in the photo above), with which the measurements are made. They, if necessary, can be replaced with better or - comfortable.

👉 Note: Be prepared immediately with something (scotch, tape) to fix the entrance locations of both wires into hollow plastic tubes holders. The fact is that the conductors in the tubes are hard not fixed and when the "probe" turns can easily come off (by virtue of the extremely clutch solder) near the base of the measuring tip.

Before starting to use a multimeter on the full program - look at our digital tester closer. In its upper part, we see a seven digital scoreboard that can display up to four digits (9999 - the maximum value). When the supply battery is discharged, an appropriate inscription appears on it: "BAT".

Under the scoreboard are two buttons. On the left button "HOLD" - hold the readings of the last value (in order not to keep in memory when rewriting in a notebook). And to the right - "Back Light" - screen illumination in blue (when measurements in poor lighting conditions). From the back on the housing of the multimeter there is a folding leg-stand (for convenient placement of the tester on the table).

The digital multimeter of the 9-volt battery of the Krone type is powered. True, to get to it, we will have to remove the rubber protective case and the back cover of the tester. Then the red is the red power element, and at the top - the fuse, which (I hope) will protect our meter from failure in case of overload.

So, before starting to use the multimeter, you must properly connect the measuring "probes" to it. The general principle is the following: black wire (it is called differently: common, com, Common, weight) is minus. We connect it to the appropriate Nest of the Multitester with the "COM" signature. Red - in the nest to the right of him, this is our "plus".

The remaining free socket on the left is to measure the DC with the limit of up to 10 amps (large currents) and - without a fuse, as evidenced by the warning inscription "UNFUSED". So be careful - do not burn the device!

Also pay attention to the warning sign (red triangle). It is written below: max 600V. This is the maximum allowable voltage measurement limit for this multimeter (600 volts).

🚨 Warning! Remember the following rule: If the measured voltage values ​​(volts) or current (amps) are unknown in advance, then to prevent the multi-set exit, install the switch to the maximum possible measurement limit. And only after that (if the readings are too small or - not accurate), switch the device to the limit below the current one.

Now, in fact, - how to use the multimeter and how to switch these very "limits"?

Working with a multimeter is needed using a circular switch with a pointing arrow. By default, it is set to "OFF" (the device is turned off). We can rotate the arrow in any direction and thus "say" to the multi-meter what exactly wants to measure or - with what maximum limit will work.

There is one very important point here! Working with a digital multimeter, we have the opportunity to measure the values ​​of both alternating and direct current and voltage. Now in industry and everyday life, an alternating current is used in the overwhelming majority. It is he "flowing" on high-voltage lines of wires from power plant generators to our homes, "ignites" our lighting lamps and "feeds" various household electrical appliances.

Alternating current, compared with constant, much easier to convert (using transformers) in the current of another (we need) voltage. For example: 10,000 volts can be easily turned into 220 and completely directed for the needs of a residential building. AC current (compared to constant) is also much easier to "extract" on an industrial scale and transmit it (with smaller losses) over long distances.

You need to use the multimeter, considering everything above. Therefore, remember by heart the following cuts:

DCV = DC Voltage - (eng. Direct Current Voltage) - constant voltageAcv = AC Voltage - (Ang. Alternating Current Voltage) - AC voltage DCA - (eng. Direct Current AMPERAGE) - DC strength (in amps) ACA - (ang . ALTERNATING CURRENT AMPERAGE) - AC voltage strength (in amperes)

Now, - We can learn to use the multimeter further. Close to the dial of your meter and you will definitely see that it shares strictly into two parts: one for measuring the constant and second - alternating voltages. Will two letters "DC" in the lower left corner in the photo above? This means that the left (relative to the "OFF" position) we will work with a multimeter, measuring constant voltage and current values. Accordingly, the right side of the multitetester is responsible for measuring the variable current.

Now I suggest you immediately consolidate the knowledge gained in practice. Show an example of using a multimeter to measure the capacitance of the conventional battery for the BIOS "CR 2032" with a denomination of 3.3 volts. Do you remember our red warning? Always set the limit higher than the measured values. We know that in the battery - 3.3V and this is a constant current. Accordingly, it is set on the circular switch "limit" of measurements on a DC scale of 20 volts.

Pay attention to the "+" mark on the battery. We apply "plus" (red dipstick), and to the reverse side - "Earth" (black).

Note: If you confuse polarity (to the plus - minus, and to minus - plus) i.e. - Change "probes" by places - nothing terrible will not happen, just before the result on the digital scoreboard you will see the "minus" sign. Measurement values ​​themselves will remain true.

So, we took advantage of the multimeter and what is the result? Look (photo above) on the digital tester scoreboard. The numbers "1.42" are displayed there. So in our battery now 1.42 volts (instead of the three). With the scope of it - in the trash bin! Reach BIOS settings with such a battery. The computer will automatically each time.

To learn how to work multimeter and effectively work with it, we need to know (remember, write down, pull out) the following notation, which we will probably meet on similar meters, regardless of their model. More perfect samples of multimeters show also the container of elements - " F "(it is measured in the Farades) and inductance -" l "(calculated in Henry -" GN ").

The next position of the switch is 600 volts on the alternating current scale. It is not better suitable for measuring the voltage in the household power grid (current - variable and the value of the scale - several times higher than the required - 220 V.). The order of "probe" in the rosette does not play.

The next position is 200 volts (here it is not necessary to measure the voltage in the outlet - the multimeter will burn!). To the right of us - the figure "200" with the "μ" icon (the micronomer is the millionth of the ampere). Such values ​​of quantities can be used in different kind of electrical circuits.

The next on the scale is "2m" (two milliamperes - two thousandth amperes). The indicator is found primarily in the transistors. Next - "200m" - similarly, but the countdown begins with two hundred millions. The next position of the switch is "10a" (the maximum strength of the current is ten amps). It is the territory of large currents, be careful! Here we will need to include a red "probe" to include in a special nest, designated in the photo as "10ADC".

Acoustic wave icon (transk) line on short circuit. What is it from this benefit? Let's look at the example.

Imagine this situation (as it turned out - very real) that part of the cables forgot to sign. The following is: On the other wing of the building (from a computer outlet of the user), we cannot say what kind of cable from a hundred belongs this particular ending and the search for a "happy end" automatically turns into a separate task

Here we are on the revenue and will come the mode of using the multitetester as the "dialer" of the cable for a short circuit. Since the tip is enclosed in the title, then we remain the following - to organize this KZ (short circuit).

In low-current networks (which includes computer LANs) it is not terrible. At the ends of the cables on both sides, we remove the protective coating on both sides, select one particular cable (which we want to find (call)) and also clean from isolation any pair of its conductors. And then - just twist them with each other, creating in the line "loop". To her, it is to show it faster in the photo than to describe words.