What can be measured with a multimeter in a car. How to use a multimeter: step-by-step instructions

The main electrical measuring instrument used by electricians, radio engineers, auto electricians, and other electronics specialists is a multimeter. The name of the instrument reflects the ability to measure several electrical quantities. Most multimeters have the ability to measure the following quantities:

• voltage (constant, alternating);
• resistance.

As additional options, multimeters can measure capacitance, alternating current, transmission coefficient h21 of bipolar transistors, and “ring” electrical circuits (determine the presence of contacts and connections).

According to the type of indication of measured values, multimeters are classified into:

• switches;
• digital.

In dial multimeters, a magnetoelectric microammeter with a system of switching shunts and diode assemblies is used as a basic measuring device. The analog scale has divisions for measuring electrical quantities. Type of dial multimeter.

In digital multimeters, the analog measured signal is converted into a digital one, then the information is processed and transmitted to a digital scale. Digital multimeters have a number of advantages over dial ones:

• increased measurement accuracy;
• clarity of indication;
• mechanical resistance to falls;
• ease of use by non-professionals.

Manufacturers produce multimeters for general and special purposes.

Special digital multimeters can be designed for:

• measurements of large electrical quantities;
• control of climatic parameters (pressure, temperature);
• measurement of parameters of radio components (resistance, capacitance, inductance).

Application of General Purpose Multimeter

A general purpose multimeter is a measuring instrument designed to measure currents, voltages and resistances in household networks, devices and cars.

A typical representative of such a multimeter is the MAS 830L device.

It is made according to the classical scheme. The device includes:

• LCD indicator14 for visualization of measurement results;
• digital scale backlight switch 2;
• self-diagnosis mode switch 1;
• mode switch;
• probe sockets 7, 8, 9;
• connector for connecting transistors 10.

The impact-resistant multimeter body is housed in a rubber casing to increase mechanical resistance.

Sequence of measurements

DC Voltage Measurement

To perform measurements, the black probe of the multimeter is connected to the COM connector (8), the red one to connector 7. This connection of the probes is used for all measurements, with the exception of measuring the value of direct current at the limit of 10 Amps.

The voltage value is measured by parallel connection of the probe to the measurement points (leads, contacts, connectors, terminals). The mode switch is set in zone 13 to the limit corresponding to the maximum possible voltage in a particular circuit. For example, when taking measurements in a passenger car, the switch is set to the 20 Volt limit. If the measured voltage is less than 2 Volts, to obtain more accurate data, set the switch to 2 V. If the measured voltage exceeds the measurement limit, the digital indicator will display the value 1 in upper case.

The digital indicator shows the polarity of the voltage (+ and - symbol).

AC Voltage Measurement

This mode is often used to control a household network 220/380 Volt 50 Hertz. To do this, the mode switch is set to zone 3 at a limit of 600 Volts. The measurement results are displayed on a digital scale. If the value is less than 200 Volts, the limit can be set to 200 Volts to increase accuracy.

When taking measurements, precautions must be taken.

Direct current measurement

Measurements are carried out by connecting probes to an open circuit. If you connect, for example, in current measurement mode, probes to the battery terminals, the device will fail. Initially the switch is set to 200m (milliamps), then to a lower one if required.

At a current limit of up to 10 Amps, the red probe is placed in slot 9. At high currents, the probe conductors may heat up.

Resistance measurement

The switch is installed in zone 11 at a limit of 200. The probes are installed in slots 7 and 8. If 1 is indicated (Fig. 4), it means that the circuit resistance is greater and the limit increases.

Indication 1 at the maximum limit indicates an open circuit.

Diode performance monitoring

The multimeter has the ability to check the performance of diodes. The switch is set to position 12. By alternately connecting the probes to the diode in different directions, the serviceability of the diode is determined. In one direction the resistance should be about 600 Ohms. In reverse switching, the resistance is almost infinite (1 is shown on the indicator).

"Continuity" of the electrical circuit

To determine the serviceability of electrical wiring using the sound method, the switch is set to position 6. The probes are connected to the opposite terminals of the controlled conductor. If there is an electrical connection (functional contacts, conductor), the buzzer will sound.

Determination of the transmission coefficient h21 of bipolar transistors

The switch is set to OFF. The transistor is inserted into connector 10 according to the polarity, base, collector, emitter (cbe) location. The switch is set in direction 5. The transistor gain is displayed on the LCD display.

Security measures

During the measurement process, the following safety precautions should be observed:

• when working with high voltages (at 200 and 600 volts), do not touch the current-carrying elements of probes, wires, and connectors;
• when taking measurements in a 220/380 Volt household network, it is necessary to use personal protective equipment (rubber gloves, insulating mat);
• when measuring high currents (10 A), it is advisable to use safety glasses to prevent sparks from entering the organs of vision;
• Current measurements should only be made during an open circuit.

A multimeter is the main measuring tool for any specialist involved in electrical circuits, including an auto electrician. No computer diagnostics can replace this simple device.

Not only every driver, but also any self-respecting man should know how to use a multimeter in a car or at home.

Why is it needed?

A multimeter is a universal electrical measuring instrument for monitoring voltages, currents and resistances in an electrical circuit. Since a modern car is more likely an electronic device than a means of transportation, the presence of a multimeter in its repair kit is necessary, even if the car owner is not an electrical specialist.

You can learn how to use a multimeter in a few minutes. The cost of such a device is small, it can provide disproportionately great help in the event of a malfunction of the vehicle’s electrical equipment.

Currently, automotive multimeters are produced specifically for use by auto electricians and car enthusiasts. They are adapted to measure electrical and other parameters related to the operation of engine systems, battery charge, and vehicle electrical equipment.

Many multimeters are classified as automotive only as a marketing technique. The parameters they measure do not always meet the needs of auto electricians, especially ordinary car enthusiasts.

Review of popular models

Let's look at some models of automotive multimeters.

F716

Manufacturer: Caltek Industrial. Designed to perform the following measurements:

• current, voltage and resistance in the mode of a conventional multimeter;
• checking the presence and parameters of fuel injection pulses (nozzles, injectors);
• checking lambda probes;
• control of the battery charging system;
• measurement of battery leakage current;
• grounding quality control;
• availability of an RS-232 bus for connecting to a laptop.

In principle, these functions, with the exception of measuring injection parameters and connecting to a computer, can be implemented on a regular multimeter.

Mastech MS6231

Purpose:

• measuring parameters in the mode of a conventional multimeter;
• temperature measurement ranging from minus 20 to plus 1000 degrees Celsius;
• crankshaft speed measurement;
• measuring the crankshaft advance angle (contact ignition);
• auto power off;
• retention of measurement results, maximum value.

The most useful function is auto power off; it will prevent the battery from discharging when work is completed. The engine speed is shown on the car's tachometer; contact ignition systems are used only on Zhiguli cars.

It features an original shape. Among the very useful functions of this multimeter, in addition to a powerful flashlight (which is sometimes very useful), is the ability to non-contactly monitor the voltage (current) in a conductor without damaging the insulation. Experienced auto electricians know how often it is necessary to pierce a needle or make a micro-cut to check the voltage in a particular conductor.

Using the special probe of this multimeter, you can check the circuit without damaging the insulation. Non-contact voltage monitoring can also be done for a household AC 380 Volt network (with the appropriate position of the mode switch). The automultimeter also has a “control” (a light for dialing).

Video - review of such a multimeter:

The following are offered as special automotive measurements:

• checking for short circuits and open circuits;
• ignition system test;
• generator control;
• control of injector pulse parameters.

A very original and useful device.

In addition to the usual functions of a multimeter, it measures engine speed. For “dummies”, the display shows which connectors to connect the probes to in a given measurement mode. Very original, but nothing more.

Video - UT105 car multimeter in operation (function overview)

The American manufacturer equips the multimeter with additional probes, alligator clips, a tip for high-voltage wires, and a temperature sensor. In general, the measuring instrument can be classified as professional.

In addition to the usual ones, the multimeter measures the parameters of injector pulses, including duty cycle, crankshaft rotation speed. There is a megohmmeter up to 40 MOhm, very useful for monitoring high-voltage wires and spark plugs. The bells and whistles include a quasi-analog scale on a digital display and automatic setting of the measurement limit. Not a bad device.

Almost an ordinary multimeter with additional functions of “continuity”, temperature measurement, a non-contact probe for high-voltage wires, measuring the ignition angle (this is a big plus), measuring direct current up to 15 Amps (not 10, as in most - and this is a plus).

The manufacturer claims shock resistance when dropped from a height of 1.5 meters (this is a double plus). At a low cost, such a device is almost ideal, both in the practice of an auto electrician and for a car enthusiast. One problem is that it is quite difficult to find it on the radio and car markets.

Which multimeter is better for an ordinary car enthusiast to choose for a car?

In principle, when choosing a multimeter for automotive use, it does not matter whether the car or a regular model of the device will be located in the trunk. If a multimeter is purchased for garage storage and use, then you can choose a car model.

The main thing is that you should always have a multimeter in your car!

It doesn't matter which one. In emergency situations of electrical equipment failure on the road or in a parking lot, it is usually necessary and sufficient for the multimeter to produce:

• measuring the voltage of the on-board network and battery;
• monitoring the battery charge from the generator;
• made a “test” of fuses, light bulbs and electrical wiring;
• leakage current measurement;
• monitoring sensor parameters, primarily resistance and voltage on the sensors.

The following additional consumer characteristics are desirable: backlighting of the digital indicator, shock-resistant housing. A simple multimeter costing up to 1000 rubles, for example MAS830L, can satisfy these parameters.

The designations of modes on most devices are standardized, therefore, having learned to work on one multimeter, you can confidently switch to using another. The “lifetime” of a multimeter in the practice of an auto electrician is a maximum of six months, in a car enthusiast – a couple of years.

The first thing to fail is the probes. This usually happens in winter: poor-quality insulation cracks in cold weather, wires break, and probes have to be replaced. Then, usually due to inattention, the 10 Ampere current measurement mode fails. After this, the dialing mode, resistance measurements and ... then it’s better to buy a new one. Therefore, it makes no sense to buy an expensive multimeter.

How to use a multimeter in a car in different modes

Let's look at the MAS830L as an example.

How to check voltage

To control the voltage on the battery, you need to connect the red (positive) probe to socket 6, the black (negative) probe to socket 5. Next, the mode switch is set to zone 1 for measuring direct voltages to a limit of 20 Volts (20V). The voltage of a normally charged battery is from 12.4 to 12.8 volts. With the engine running, the voltage at the battery terminals should increase to 13.5 - 14.5 Volts. This shows the car.

How to measure current

Most often, this mode is used to measure leakage currents in the battery circuit.

Current measurement is carried out in an open circuit.

To measure the leakage current, you need to disconnect the positive terminal of the battery, then switch the mode to the 10A position (on mode 8). Connect the positive probe to socket 4, the negative probe to socket 5. Connect the red (positive) probe to the “+” terminal of the battery, the black (negative) probe to the disconnected positive terminal.

Be careful - the positive terminal should not touch metal elements of the body and engine.

The multimeter display will indicate the leakage current. A leakage current of up to 0.2 Amperes is considered normal. For more accurate measurements, you can switch to a lower measurement limit. In this case, switch the red probe to slot 6.

Video - how to measure battery current leakage with a multimeter:

Resistance measurement

To check the serviceability of the light bulb, set the mode switch in resistance measurement zone 2 to a limit of 200 Ohms. Connect the probes to the light bulb. The indicator shows the lamp resistance value.

If the indicator displays 1 in uppercase, it means the light bulb is faulty or has a resistance greater than 200 Ohms.

The resistance of the sensors is measured in a similar way.

"Continuity" of fuses and circuits

The mode switch is set to position 7. The probes are connected to the fuse terminals. If it is working properly, a buzzer will sound. The wires are connected in the same way. The probes should be connected to the stripped areas at the beginning and end of the wire.

Diode check

Required when checking the generator diode bridge. The switch is set to position 3, the probes are directed to the diode being tested. In one connection of the probes, the resistance should be infinite (as in the previous figure - the indicator will display 1), in the other (direct) - from 500 to 700 Ohms.

This multimeter also has a mode for measuring the gain of bipolar transistors, but it is not used in car enthusiast practice.

Be sure to include a multimeter as part of your on-board instrumentation.

A radio amateur's home workshop must have a universal measuring device (tester), since not a single amateur radio design, even the simplest one, can do without adjustment.

There are times when the assembled structure does not work well or does not breathe at all, and in such cases a measuring device comes to the rescue. What about amateur radio designs? In home life, such a device is simply a necessary thing.

Today, the most popular digital measuring instruments are: multimeters. They are easy to use, multifunctional and relatively cheap. Their prices are also different and depend on the quality of workmanship, the number of functions and parameters of the device.

Any multimeter, regardless of price, has a standard set of functions that all models support: this voltage, current And resistance. And when you buy a device, be sure to choose one with modes calls And sound generator, and in terms of price, choose the middle - between the cheapest and the most expensive. From the middle ones, you can take the one for which the seller gives an acceptable guarantee.

Multimeter. Appearance.

The placement of measurement parameters for all multimeters is standard, and for convenience they are divided into sectors and outlined with lines. In the center there is a round switch, which selects the parameter and measurement limit needed at the moment.

We measure DC voltage.

Let's start with measurement DC voltage: This sector is divided into five subranges with measurement limits:

1. 200mV(millivolt);
2. 2000mV(millivolt);
3. 20V(volt);
4. 200V(volt);
5. 1000V(volt).

indicating the maximum value of the subrange within which the measurement is carried out.

Insert the measuring probes into the corresponding sockets as in the photo. The red probe is usually called " positive", and black, " general" or " minus».

Let's look at an example using a AA battery.
It is known that its voltage is 1.5 Volts, and to measure it we choose the limit " 20 ", which corresponds to the range from 0 to 20 Volts.

We take the measuring probes of the multimeter and touch them “ positive" And " minus» battery contacts and the indicator showed a voltage value equal to 1.49 Volta. The measurement is completed.

As you can see, everything is very simple - the main thing is to choose the right measurement limit.

We measure a voltage of an unknown value.

There are times when the voltage value is unknown even approximately, and in order not to burn the multimeter, the switch is switched to the maximum measurement limit " 1000 ", which corresponds to the range from 0 to 1000 Volts. And then, gradually reducing the range, the corresponding value of the measured voltage is found.

For example. We don't know what voltage our battery has, so we'll start at the limit." 1000 " We take the measuring probes of the multimeter, touch them to the battery contacts and see zeros on the indicator. Zeros indicate that there is no voltage or its value is too small.

Go ahead. Move the switch to position " 200 "And again we touch the battery contacts with the probes. Now voltage readings have appeared on the indicator, and this is almost enough to understand what it is 1.4 Volta.

However, we have a zero ahead of us, and it just means that we can lower it further and measure the voltage more accurately. Let's go down to the limit" 20 " The indicator displayed the real voltage of our battery, namely 1.49 Volta.

In this way, without knowing the exact value of the measured current, voltage or resistance, its true or close to the true value is found.

There are still times when the multimeter indicator displays a unit ( 1 ). This indicates that the measured voltage or current is higher than the measurement limit that is set. In this case, you need to move up a step. Try to avoid this as little as possible.

We have two subranges left unconsidered: this 2000mV(millivolt) and 200mV, which are designed to measure small voltages. As a rule, they work on these subbands when they adjust the operating modes of transistors or transition stages in amateur radio circuits.

2000 mV – corresponds to the range from 0 to 2 Volts;
200 mV – corresponds to the range from 0 to 200 mV (millivolts).

Another nuance that needs to be mentioned is when, when measuring direct voltage or current, you will not know where “ positive" or " minus» contacts and accidentally mix them up - there’s nothing scary here. Just on the left side in front of the numbers there will be a sign “ minus».

In this way, the polarity of the voltage can be determined.

We measure alternating voltage.

The process of measuring alternating voltage is similar to measuring direct voltage with the only difference that there is no need to determine where " plus" And " minus" As an example, let’s measure the voltage of a household electrical network of 220 Volts.

Attention! Be especially careful and extremely careful when measuring high voltages. Do not touch the metal parts of the probes!!!

This sector is divided into only two subranges with measurement limits:

200 Volt;
750 Volt.

indicating the maximum value of the subrange within which the measurement is carried out. The measuring leads are the same as when measuring DC voltage.

Selecting the measurement limit 750 Volt. Additionally, we make sure that the insulation of the wires and probes of the multimeter is in good condition. Once again we check the correctness of the selected measurement limit, and only after that we measure the 220 Volt network voltage.

As you can see, everything is very simple.
And here we also do not forget that when measuring an alternating voltage, the value of which is unknown, to determine it, we begin only with maximum limit, namely with 750 Volt.

After finishing work with the multimeter, be sure to turn it off by moving the switch to the “ OFF“, otherwise you won’t have enough batteries.

To finally understand how to measure voltage with a multimeter, watch this video.

There is a measuring device that combines the functions of several similar devices. It's called a multimeter. How to use it will be discussed in this article. It is mainly designed to measure line voltage, resistance and electric current.

New features

Manufacturers add new features to modern modifications of these devices:

• diode ringing;
• capacitor capacitance measurement;
• temperature measurement;
• checking the operating parameters of transistors;
• current frequency measurement;
• sound probe.

Classification of the equipment in question

All modern multimeters can be divided into:

• Digital ones, which are the most popular because they are relatively inexpensive, perform many functions, and are easy to use.
• Pointer, in which readings are taken on a scale with an arrow. They have a small error due to the difference in this scale. However, the device is universal, capable of replacing ampere, ohm and voltmeters.

In the future, we will mainly consider how to use a digital multimeter, and at the end of the article we will return to its pointer variety with some inserts on it along the course of the presentation of the material.

Checking the resistance

Before this work, the multimeter must be prepared for it. The device has a toggle switch that switches to the position corresponding to the minimum measurement of the obtained value of the desired value. Such measurements should be carried out with the circuits completely de-energized. To do this, the equipment whose resistance will be measured is disconnected from the electrical network, or batteries such as batteries are removed from it.

How to use a multimeter? The instructions stipulate that the performance of this device should be checked by connecting the ends of the corresponding probes. The device should show “0” either on an electronic display or using a magnetic needle. If this does not happen, then it is necessary to make adjustments using the “Set” knob. 0". All other cases require battery replacement.

Measuring DC voltage

Let's look at how to use a digital multimeter to determine this indicator. Typically the sector responsible is divided into 5 ranges:

• 200 mV;
• 2000 mV;
• 20 V;
• 200 V;
• 2000 V.

However, their number may vary and include other limit values. This shows the maximum voltage that can be measured in this range. Probes intended for measurements are inserted as follows: black (common or negative) is inserted into the lower hole located on the right, and red (positive) into the one located slightly higher.

In order to measure the voltage of a 1.5 V battery, set the switch to position 20. Using the appropriate test leads, touch the opposite poles of the battery and look at the screen, and the number 1.49 should appear on it.

If the measured voltage is unknown, then you need to start with the highest range - 1000 V, so as not to burn the device, gradually reducing it until the required value is found. The fact that there is no voltage in this range will be indicated by zeros on the display. If there are zeros ahead, but some number has already appeared, you can move the device to a position that is a multiple of the number of zeros ahead compared to the occupied one in which this number was recorded. This is necessary if you need to obtain more accurate data. If strong accuracy is not required, then you can take readings at the stage from zeros to a significant number. Sometimes the multimeter does not burn out when setting a smaller range than the measured value, but shows “1”. However, this condition should not occur too often.

We looked at how to use a multimeter correctly. If you accidentally confuse the negative and positive probes, nothing bad will happen, the number displayed on the display will simply have a “-” sign. Small ranges are used when working with amateur radio circuits and transistors.

We measure alternating voltage

It doesn’t matter here where the plus and minus are on the probes. The work is carried out with high voltages, so you cannot touch the non-insulated parts of the probe during measurements.

This sector is divided into two:

• 200 V;
• 750 V.

Test leads are placed into the multimeter in the same way as they were inserted when measuring DC voltage. To measure the indicator in question in the outlet, you need to set the range to 750, since 220 V is greater than 200. After finishing work, turn the device to the “Off” position.

Checking the integrity of the network

To do this, you need to ring the last one. To perform this operation, a device with a magnetic needle deviating from “0” or with a dead battery can be used. Let's look at how to use a multimeter in this case.

The arrow should respond to the connection of the ends of the probes. Digital instruments should display a value close to zero, which may vary due to transient current resistance from the ends of the probes. When they open, the arrow is set to the infinity point on the corresponding devices, and on digital devices a reboot will begin or “1” will appear. If the ends of the probe are placed against the direct conductor, a zero value should appear.

If there is a built-in circuit testing function, this in relation to wires and low-impedance operating circuits should be carried out by setting the toggle switch to this position. In this case, a signal will be given, making the display unnecessary. If there is a network break, there will be no sound, and the device will show near-zero values. This example shows how to use the DT-832 multimeter.

Using the device as an ammeter

In order to determine the current strength, the device is connected to an electrical circuit. If present, the toggle switches of the device are turned off, the test is carried out with a special probe. In an active circuit, the current must be equal to 0. The place where measurements are made must be dry. It is better to wear gloves on your hands before working.

Capacitor check

It passes alternating current through itself. To check the capacity, the condition must be met that for the device it must be 0.25 μFarad, that is, the minimum.

When performing a check, perform the following actions:

• determine the positive and negative poles of the capacitor;
• remove static electricity from it;
• the multimeter is moved to the ringing position or determining the resistance;
• The probes of this device touch the terminals of the capacitor.

In this case, it is most convenient to use an analog (pointer) multimeter, since it controls the movement of the needle. The capacitor is working if the device beeps or shows zero resistance. The displayed unit indicates that there is a break inside the capacitor.

Pointer multimeter

How to use a dial multimeter? Basically exactly the same, only the readings are not taken electronically from a digital display, but are read on a scale, along a frozen arrow. The manufacturers produced a combined pointer-digital device. It can be used to determine alternating and direct current, resistance and capacitance of capacitors, test diodes, test connections and test batteries.

According to user reviews, this type of multimeter is considered a worse analogue compared to a digital device. This is due to the fact that the needle may jam, and the accuracy of the device is lower compared to a digital one. It is recommended to use it when it is necessary to take measurements at two points simultaneously in conjunction with a digital multimeter when monitoring their mutual dynamics.

Using the device in cars

How to use a multimeter in a car? In this case, the most popular functions are ringing and voltmeter. The most common is the DT-832 multimeter. We'll look at how to use it further.

The number 832 indicates that the device is equipped with a sound indication. Must be operated in a temperature range of 0-40 °C. Powered by a Krona battery. With its help, you can measure direct current up to 10 A, alternating voltage up to 750 V, direct voltage up to 1000 V, resistance up to 2000 kOhm, and the health of transistors and diodes.

A black probe is inserted into the “COM” socket; the two above are intended for the red variety. The current strength can be determined for additional equipment for the vehicle. In a 220 V network, this indicator cannot be measured.

You should choose a car multimeter based on the following points:

• It is better if the model is equipped with a sound alert;
• you need to choose a device that has a fuse that can be replaced in the event of an erroneous action by the user;
• the body must be rubberized.

In addition to the multimeter discussed above, other similar devices can be used in cars. The most compact, having small dimensions that coincide with two matchboxes, is the DT-182 multimeter. How to use it? Similar. It is designed to measure resistance, voltage and current. You can also test transistors, diodes and batteries with it and check connections. This device is powered by a 23A type little finger battery with a voltage of 12 V. This circumstance is negative, since this battery fails quite quickly. However, the multimeter has a built-in warning function that warns you when the battery is running low.

This device has the following ranges:

• 200 mV-500 V - for constant voltage;
• 200-500 V - for alternating voltage;
• 200 Ohm-2000 kOhm - for resistance;
• 200 µA-200 mA - for direct current;
• 1.5-9 V - for testing batteries.

It is not protected from damage when voltage is applied when measuring resistance. The conductive layer on low-resistance resistors burns out, which makes the values ​​of the microammeter and ohmmeter unknown. The ADC IC may also fail. In this case, it is easier to dispose of the device than to try to repair it. However, repairs can be carried out according to a diagram that you can draw yourself after removing the back cover of the device. In this case, you need to indicate the ratings on the sheet, after which you should attach it to the back cover of the multimeter and use it as needed.

Finally

In this article we looked at how to use a multimeter. This is an inexpensive but multifunctional device with which you can ring the connection, set the current strength, check the voltage of both direct and alternating current, and test batteries. Some devices allow you to measure temperature, set the operating parameters of transistors, and also perform some other functions.

A multimeter is one of the inexpensive measuring instruments that is used by both professionals and amateurs who repair home wiring and electrical appliances. Without it, any electrician feels like he has no hands. Previously, three different instruments were required to measure voltage, current, and resistance. Now all this can be measured using one universal device. Using a digital multimeter is very easy.

The main two rules to remember:

• ⚡ where to connect the measuring probes correctly
• ⚡ in what position should the switch be set to measure different quantities?

Multimeter appearance and connectors

On the front of the tester, all the inscriptions are made in English, and even using abbreviations.

What do these inscriptions mean:

• OFF - the device is turned off (to prevent the device batteries from running out, set the switch to this position after measurements)
• ACV - measurement of variable U
• DCV - constant U measurement
• DCA - DC current measurement
• Ω - resistance measurement
• hFE - measurement of transistor characteristics
• diode icon - continuity test or diode test

Switching modes occurs using the central rotary switch. When you first start using your digital multimeter, it is recommended that you immediately mark the pointer mark on the switch with contrasting paint. For example like this:

Most device failures are due to the incorrect choice of switch position.

Power is supplied from a Krona battery. By the way, by looking at the connector for connecting the crown, you can indirectly judge whether the tester was assembled in a factory or somewhere in Chinese “cooperatives”. With high-quality assembly, connection occurs through special connectors designed for the crown. Lesser quality options use regular springs.

The multimeter has several connectors for connecting probes and only two probes. Therefore, it is important to correctly connect the probes to measure certain quantities, otherwise you can easily burn the device.

The probes are usually of different colors - red and black. The black probe is connected to the connector labeled COM (translated as “common”). Red probe into the other two connectors. The 10ADC connector is used when it is necessary to measure current from 200mA to 10A. The VΩmA connector is used for all other measurements - voltage, current up to 200mA, resistance, continuity.

The main criticism is caused by the factory probes that come with the device. Almost every second owner of a multimeter recommends replacing them with better ones. However, their cost can be comparable to the cost of the tester itself. As a last resort, they can be improved by strengthening the bends of the wires and insulating the tips of the probes.

If you want high-quality silicone probes with a bunch of tips, then you can order them with free shipping on AliExpress.

Previously, pointer testers were also widely used. Some electricians even prefer them, considering them more reliable. However, due to the large error of the measurement scale, it is less convenient for ordinary consumers to use them. In addition, when working with a dial multimeter, it is imperative to guess the polarity of the contacts. For digital ones, if they are connected to the poles incorrectly, the readings will simply be displayed with a minus sign. This is normal operation and will not damage the multimeter.

Basic Multimeter Operations

Voltage measurement

How to use a digital multimeter to measure voltage? To do this, set the switch on the multimeter to the appropriate position. If this is the voltage in the outlet at home (alternating voltage), then flip the switch to the ACV position. Insert the probes into the COM and VΩmA connectors.

First of all, check that the connectors are connected correctly. If one of them is mistakenly installed in contact 10ADC, a short circuit will occur when measuring voltage.

Start measuring from the maximum value on the device - 750V. The polarity of the probes does not play any role at all. It is not necessary to touch the zero with a black probe, and the phase with a red one. If a much lower value is displayed on the screen, and the number “0” appears in front of it, this means that for a more accurate measurement, you can switch to another mode, with a smaller voltage level scale that your multimeter allows you to measure.

When measuring DC voltage (for example, electrical wiring in a car), switch to DCV mode.

And you also start measuring from the largest scale, gradually lowering the measurement levels. To measure voltage, you need to connect the probes in parallel to the circuit being measured, while using your fingers to hold only the insulated part of the probe so as not to get under voltage yourself. If the display shows a voltage value with a minus sign, this means that you have reversed the polarity.

ATTENTION: when measuring voltage, be sure to check that the multimeter scale is set correctly. If you start measuring voltage with the DCA switch in the on position, i.e., measuring current, you can easily create a short circuit right in your own hands!

Some experienced electricians recommend holding both probes in one hand when measuring the voltage in an outlet. If the probes are poorly insulated and breakdown, this will allow you to protect yourself to some extent from electric shock.

The multimeter operates on a battery (a 9-volt crown is used). If the battery starts to run low, the multimeter starts to lie shamelessly. In the outlet, instead of 220V, it may seem like 300 or 100 Volts. Therefore, if the device readings begin to surprise you, first check the power supply. An indirect sign of battery discharge can be chaotic changes in the readings on the display, even when the probes are not connected to the object being measured.

Current measurement

The device can only measure direct current. The switch must be in the – DCA position.

Be careful! When measuring current, if you do not know approximately what limits the current will be, it is better to start measuring by inserting the probe into the 10ADC connector, otherwise measuring a current of more than 200mA at the VΩmA connector can easily blow the internal fuse.

Here, probes, unlike voltage measurements, must be connected in series with the object being measured. That is, you will have to break the circuit and then connect the probes into the resulting gap. This can be done in any convenient place (at the beginning, middle, end of the chain).

In order not to constantly hold the probes with your hands, you can use alligator clips for connection.

Know that if, when measuring current, you mistakenly set the switch to ACV mode (voltage measurement), then most likely nothing bad will happen to the device. But if it’s the other way around, the multimeter will fail.

Resistance measurement

To measure resistance, set the switch to position - Ω.

Choose the desired resistance value or start again with the largest one. If you are measuring resistance on some operating device or wire, it is recommended to turn off the power from it (even from the battery). This way the measurement data will be more accurate. If during measurement the value “1, OL” appears on the display, this means that the device is signaling an overload and the switch needs to be set to a larger measurement range. If “0” is displayed, then on the contrary, reduce the measurement scale.

Most often, a multimeter in resistance mode is used during repair work, to check the functionality of household appliances, the serviceability of the windings, and the absence of a short circuit in the circuit.

When measuring resistance, do not touch the bare parts of the probes with your fingers - this will affect the accuracy of the measurements.

Calling

Another operating mode of the tester that is often used is dialing.

What is it for? For example, in order to find an open circuit, or vice versa - to make sure that the circuit is not damaged (checking the integrity of the fuse). The level of resistance is no longer important here; it is important to understand what is wrong with the circuit itself - whether it is intact or not.

It should be noted that there is no sound signal on the DT830B.

For other brands, as a rule, the signal is heard at a circuit resistance of no more than 80 Ohms. The dialing mode itself occurs when the pointer is positioned - checking the diodes.

It is also useful to check the integrity of the probes themselves by testing them by connecting them to each other. Since with frequent use they may be damaged, especially at the point where the wire enters the probe tube. Before each measurement, be sure to make sure that there is no voltage in the area where you will connect the test leads, otherwise you may burn the device or create a short circuit.

Safety precautions when working with a multimeter

• ⚡ do not take measurements in a damp room
• ⚡ do not switch measurement limits during the measurements themselves
• ⚡ do not measure voltage and current if their values ​​are greater than those for which the multimeter is designed
• ⚡ use probes with good insulation

I hope this material helped you become familiar with the basic operating parameters of a multimeter. And you can safely and productively use it during repair work.