How to use the multimeter
The everyday life of a modern person is surrounded by consumers of variable (household appliances, power tools) and constant (cars) current. All electrical devices are assembled according to compiled electrical circuits, the failure of components of which leads to breakdown of complex mechanisms. A house worker, armed with special equipment and the ability to understand the intricacies of electrical wires, can not only find the cause of the loss working capacity of a wall plasma or an automatic washing machine, but also to return old paints to the TV screen, and to make the owner happy with an irreplaceable buzz assistant. A multifunctional multimeter is a must for every home wizard, so it's important to know how to use it properly.
1What is a multimeter
- 1.1Scheme of operation of an analog tester and a digital multimeter
2Purpose of the device
- 2.1.1Video: how to use a multimeter. Application in home and car repair
3Varieties of multimeters
- 3.1.1Video: how to use the multimeter and current clamp DuMa8819
- 3.1.2Photogallery: the best digital testers of 2018
- 3.1.3Table: rating of models of digital testers of 2018
4Instructions for use
- 4.1Introduction to the Multimeter Language
4.2Voltage measurement with multimeter DT830
- 4.2.1Video: how to measure the voltage in a 220-volt outlet for beginners
4.3Measuring the current with a multimeter DT830B
- 4.3.1Video: how to measure the current in a flashlight
- 4.4.1Video: multimeter resistance measurement
- 4.6Check capacitors, diodes, transistors
4.7Typical malfunctions of digital multimeters and their causes
- 4.7.1Table: common malfunctions of digital multimeters
4.8Tips for using the multimeter
- 4.8.1Video: how to use a multimeter
- 5Reviews about multimeters
What is a multimeter
A multimeter is an apparatus that measures electrical current parameters. And the tester - another device name - combines the functions of measuring devices, which determine the current strength, the voltage of the network and the resistance of the conductor. With the help of a multimeter, the presence of discontinuities in electrical networks is searched for, the operability of electronic components is checked: diodes, capacitors, triodes and other elements.
Easy, compact, easy-to-use tester - an indispensable assistant to the home craftsman, who will help quickly and accurately to determine the cause of the malfunctions in the electrical circuits of household appliances, cars, home electrical wiring, power tools.
Scheme of operation of an analog tester and a digital multimeter
In the beginning, the multimeters were analog (switch) and were called testers. They are supplied with two wires with probes, which close the sections of electrical wiring, electronic components, contacts. The result of the measurements was determined by the position of the arrow on one of the scales: separately for the voltage, its own for the current, individually for resistance.
Often scales make different colors to improve visual perception. The main nodes of the analog multimeter: a permanent magnet, a movable induction coil, an arrow connected to it and a counter-pressure spring.
The main mechanism in the analog tester is the arrowhead, which is pretty sensitive electromechanical device, made in the form of a miniature coil suspended from springs. The current passing through coils of the coil placed in a magnetic field turns it to a certain angle, thereby deflecting the arrow - fixed on it - and, overcoming the resistance of the spring, establishes in a specific position. This position of the arrow on the marked scale in the form of an arc and is the measured value of the desired parameter..
The force with which the spring counteracts the driving force of the magnetic induction is directly proportional to the strength of the current passing through the inductive coil. Therefore, the scale of the ammeter and the voltmeter in the switch tester has a linear gradation..
It is clear that the accuracy of such a tester depends on several factors: position in space, mechanical action (for example, hand trembling), ambient temperature. In the analog multimeter there is a special regulating device that helps to output the arrow to zero before the measurement starts.
The pointer device in the device is simple.
Its design consists of a set of carefully selected high-precision resistor shunts of different denominations, several diodes, a microammeter and its own power supply used for measuring resistances..
The digital multimeter is much more complicated and consists of a set of integrated circuits specially designed for a particular measurement. Schematic diagram of the digital meter is 100% dependent on the type of components used (diodes, transistors, resistors and other semiconductor elements), electrically connected among themselves on a common semiconductor basis (substrate), so to explain the principle of the device it is much more convenient to use a structural scheme that is the same for all testers of this type..
At a cost, a digital meter is not much more expensive than a switch analog, because mass production of microelectronics chips has long been established, so their cost is low. The convenience of using a digital multimeter is its merits:
- visibility (figures are perceived visually more familiarly than the position of the arrow on a finely graded scale);
- Automatic selection of the measuring range (volts, amperes or ohms).
Purpose of the device
Compact, pocket type multimeters serve to measure the characteristics of an electric current. But the range of measurements of digital analogs is much wider. They can measure capacitance of capacitors, inductance parameters, current frequency, heating temperature of conductors. You can determine the range of the parameter change, the percentage of measured values of the same type. The only function that is not available for them is the display of the measurement dynamics. But the arrow tester with ease demonstrates the intensity of changes in the speed of movement of the arrow (instantaneous, gradual, very slow). Analog multimeters can also be provided with additional functions, but then the testers will become cumbersome, heavy, inconvenient to use.
At home, a multimeter checks, as a rule, the absence or presence of a current in the supply wires. In other words, the fact of cable or conductor breakage is investigated, as well as the state of contacts in electrical circuits.
In these cases, the instrument switches to the ohmmeter function. More experienced users can measure voltage, frequency and amperage in the mains. Advanced owners of a multifunctional device check working capacity:
- electronic components in microcircuits of many kinds of home appliances - television sets, computers, washing machines and other home electric devices;
- power tools;
- on-board network of cars;
- other electrical mechanisms.
Until recently, the tester was in the arsenal of only electricians and radio amateurs, today it is owned by millions of users because of the ease of management work, small cost, compactness, the presence of a variety of objects for measuring the parameters of DC and AC in our daily reality.
Video: how to use a multimeter. Application in home and car repair
Varieties of multimeters
It is important to know that multimeters with different sensitivity ranges are used for different purposes. It is this most important parameter that determines the scope of each particular model. The multimeter that measures the voltage of the cans in the car battery will not be able to measure the low voltage voltage of the current sources, since their values are expressed in millivolts. At home, multimeter measures fuses, sockets, incandescent lamps, heating elements, integrated circuits, transistors, automotive electronics. With all these measurements, the digital multimeter, which is most popular among domestic craftsmen, can easily cope.
The very name of the multimeter - most accurately indicates the purpose of this multifunction device. There are so many varieties of testers that anyone can buy a model that meets his requirements for this device. And requests can be to design, a range of measured values, a set of functions. Today's multimeter, in addition to measuring capabilities, can be endowed with the possibilities of various calculations and the construction of a graphic representation of signals. Digital and analog models have already been said enough. Consider multimeters of other types.
It is known from school physics that a voltmeter is connected in a circuit in parallel, and an ammeter is connected in series. In order to create a gap in the high-voltage circuit for measuring the amperage, pliers were invented. The first versions of electric shovels were presented in the form of a transformer, the ammeter connected to the secondary winding. The indications of such a device had to be recalculated, so when measuring the current strength, the influence of the transformation coefficient was not taken into account. Such mites could only measure AC, they do not work with a constant current. In modern current meters, instead of an ammeter, there is a Hall sensor, which is able to detect and fix the presence and intensity of the field in both AC and DC.
There are two types of measuring ticks: professional for measuring networks with voltages above 1000 V and household - voltage less than 1000 V. The design of devices of this type is continuously being improved and today, with their help, such complex tasks are being solved:
- Measuring the amperage at any part of the network that is energized.
- Determination of the actual power consumption of any electrical device included in the network.
- Measuring the actual load in the electricity network of a house or a separate apartment at this time.
- Identify illegal connections to the grid.
- Checking household appliances for insulation breakdown and current leakage to the housing.
Video: how to use the multimeter and current clamp DuMa8819
Photogallery: the best digital testers of 2018
Table: rating of models of digital testers of 2018
|Manufacturer country||Make||Purpose||Advantages||disadvantages||Price, rub||Rating|
|Best Budget Multimeters|
|China||MASTECH M830B||For accurate measurement of current strength, DC and AC voltage, ringing semiconductors, determining the gain of transistors||High accuracy of readings, convenient control, maximum functionality. A pleasant impression is left by soft feelers and a clear display||There are no lights and auto-off features||500||,|
|China||RESANTA DT830B||For measurements in everyday life of current, voltage, resistance, checking the operability of diodes or transistors in the on-board network of cars||20-position switch, overload protection, confident operation at -20 to +50o C, the device is powered by a 9-volt CRONA battery.||No auto shut-off function when the battery is low, no buzzer, thin wires in the probes||220||,|
|China||PROCONNECT DT-182||For testing diodes, transistors, batteries||Compactness (100x50x20 mm), high-quality materials, rich set of functions and parameters, accuracy of voltage measurement (, %), current strength (,%), resistance (1%)||No auto shut-off, thin wires||260||,|
|The best multimeters for home|
|China||UNI-T UT33A||For measurements in everyday life of current, voltage, resistance, checking the operability of diodes or transistors in the on-board network of cars||When measuring resistance and voltage, the instrument automatically determines the appropriate range, there is a separate panel for testing working capacity of transistors, shutdown in the absence of activity for 30 minutes, powered by two AAA batteries with voltage, AT.||No backlight||870||,|
|China||CEM DT-912||For measurements in everyday life of current, voltage, resistance, checking the operability of diodes or transistors in the on-board network of cars||High reliability, accuracy, convenient control, ergonomics, compactness, there is protection against moisture and mechanical impact, additional illumination of the LCD screen||Tons of wire test leads||900||,|
|The best testers for cars|
|USA||FLUKE 28-II||Professional tester for solving the most difficult tasks related to the repair of electric cars||It is able to hold readings, illuminate the display, the case has heat resistance, airtightness and impact resistance, it is designed for operation in the harshest conditions, there is a thermometer, a low-frequency noise filter, the choice of ranges is selected manually or automatically, soft wires with probes, smooth adjustment of operating modes.||High price||35000||,|
|Russia / China||ELITECH MM 100||For car enthusiasts for troubleshooting in an auto electronics and measuring current, voltage, resistance||Affordable price, easy to use, reliability, there is a sound buzzer||Thin wires with probes||260||,|
|The best professional multimeters|
|China||CEM DT-9979||Multifunctional multimeter for various purposes||Modern design, comfortable stand-off, shock protection, mechanical damages, moisture and dust, automatic power off, LCD screen backlight, capacious memory for 10000 values, degree of protection IP67, the ability to plot, analyze results, measure rms values, there is Bluetooth with which you can quickly reset the data to PC||High price||22000||,|
Instructions for use
An unprepared person may find it difficult to manage this device. Buttons, switches, names in English and other not very clear things. But in fact there is nothing tricky, if one understands the principle of measuring various parameters..
The two main rules that you need to remember first:
to which contacts you need to connect the probes correctly;
in which position the switch is set to correctly measure different values.
Introduction to the Multimeter Language
Almost all models of multimeters are made in China, therefore the names on them are written in English.
The Latin letters are abbreviated as:
- ON / OFF - (Eng. off switch) enable / disable the multimeter.
- DCV = DC Voltage - (eng. Direct Current Voltage) is a constant voltage.
- ACV - AC Voltage - (eng. Alternating Current Voltage - alternating voltage.
- DCA - (Eng. Direct Current Amperage) - the power of direct current in amperes.
- ACA - (Eng. Altenating Current Amperage) - AC power in amperes.
- ᘯ - resistance measurement.
Voltage measurement with multimeter DT830
Preparing the multimeter for the beginning of the AC voltage measurement:
- the switch is placed in the ACV region at a maximum division of 700;
- Insert the wire ends with probes into the COM connectors (black wire) and VᘯmA (red wire);
- touching the phase and zero probes (the color of the wires does not matter), the multimeter must be connected in parallel to the measured network.
If the display shows a much smaller digit than 700, and before it will be zero, then the switch should be rearranged to a lower value of voltage - 200.
When measuring the DC voltage, the wires with the probes remain in their sockets, and the switch is scrolled to the DCV area. The order of the measurements is the same: start with the largest modes and gradually switch to the desired level. Important note: when measuring the DC voltage on the positive terminal, place the red probe, and on the negative terminal, the black wire. However, if the polarity is incorrect, the display shows a value with a minus sign.
Video: how to measure the voltage in a 220-volt outlet for beginners
Measuring the current with a multimeter DT830B
This type of device can measure the strength of only direct current. Sequencing:
- the switch is put into DCA mode;
- the black wire remains in the COM connector, the red wire is best inserted into the 10 A connector (if the approximate strength of the measured current is not known).
If the device shows a small value, then rearrange the red wire to the VᘯmA connector..
The current strength of an alternating current of more than 10 amperes is measured by means of electrical clamps. Multimeters for such parameters are simply not calculated and can simply burn..
Video: how to measure the current in a flashlight
In order to measure the resistance it is necessary:
- switch to the resistance measurement zone - ᘯ;
- check the serviceability of the multimeter, closing the test leads against each other (on the scale should appear zero, and the buzzer to sound);
de-energize the object to be measured;
- set the largest resistance value and gradually decreasing the level of values, find the position of the switch, at which non-zero digits appear on the display.
Video: multimeter resistance measurement
This technique is used to find out: if there is a break in the chain or it is not damaged. For the ringing, the switch is placed in the diode check position.
Check capacitors, diodes, transistors
The purpose of the event is to determine the presence of resistance, in the same way as the wire rope. The procedure is as follows:
- the black wire is inserted into the COM connector;
- red tip from the probe - in the connector VᘯmA;
- a black feeler is placed on the cathode of the diode (sign -);
- The red probe closes the anode (+ sign).
On the multimeter display, the digits indicate the value of the forward resistance of the diode. If the polarity is reversed (the probes are interchanged), the number one (the diode is defective) should be displayed on the screen. If a unit appears when measuring the forward resistance - the diode is burned out.
Typical malfunctions of digital multimeters and their causes
First of all, you should check the operation of the battery. If necessary, replace the CROWN. Do not leave the probe in the socket "10A" after the measurement is completed! A short circuit will burn out the tracks of the PCB under the switch. It's not recovering!
Table: common malfunctions of digital multimeters
|The display on all limits shows random numbers much larger than zero||Multimeter ADC is defective||replace the ADC|
|the instrument overstates the reading||low battery||replace the battery|
|temperature (M838, M890C +, G, MY62, 64) is measured only with a thermocouple||fuse blown 200mA||replace fuse|
|do not display individual segments of the display||in the old models of testers there were cases of a bad pressure of the LCD display to the current-carrying rubber||glue to the glass of the LCD (under the press frame) a strip of electrical tape|
|M830 series: 1. when measuring the voltage, the instrument overstates the reading or goes off scale, it may not be reset||1. burned R6 (100 Ω ±,%), most often; 2. burned R5 (900 Ohm ±,%), is less common. Visually the resistors can look whole.||replace. check C6 and Q for breakdown.|
|2. when measuring voltages on the upper limits, a strong underestimation of the readings||the probit (leakage) in C6 mF||check by replacement|
|3. when measuring resistances (200Ω, 2KΩ), a slow count, a gradual decrease in readings||Defect in C3 mF||check by replacement|
|4. when measuring resistance (ranges 200Ohm, 2Kohm) slow count, gradual increase in readings||Defect in C5 mF||check by replacement|
|5. when measuring the alternating voltages, the readings go (20 - 40 units)||loss of capacity C3 mF||check by replacement|
|6. when measuring resistance, the display shows zeros||the transistor Q1 (9014), connected by a diode||replace|
|7. when measuring the resistance of glitches, other modes work||the transistor Q1 (9014) connected by a diode is defective||check by replacement|
|9. the instrument sets the reading long||Defect in C3 mF||check by replacement|
|10. when the current is measured||faulty resistors R7 (9 Ohm), R8 (1 Ohm)||check by replacement|
|11. at all measurements highlights "1"||defective ADC, bad soldering or short circuit||for a working ADC, the voltage between terminals 1 and 32 is 3V *)|
|M890 series: 1. Do not zero on frequency, can lie on other modes||IC8 - 7555 is faulty||check by replacement|
|characteristic faults of devices on the ADC 7106: 1. When measuring the DC voltage, if you change the polarity of the probe connection, the instrument reading is different from the original||1. the capacitor connected to the output of the 27 ADC is defective. 2. the capacitor connected to terminals 33 and 34 is defective.||check by replacement|
|2. when the probes are short-circuited in the DC voltage measurement mode, the display readings differ from zero in several digits||the capacitor connected to terminals 33 and 34 (high leakage current) is defective||check by replacement|
Tips for using the multimeter
How to properly work with a multimeter is described in detail in this video.
Video: how to use a multimeter
Reviews about multimeters.
Feedback about Multimeter Mastech M830B
Merits took in the store. Works fine. The case is small, sturdy. It feeds on the "crown it is necessary to untwist the case. "Crohn" there in the fenced off place - does not hang around the body. Probes are also more or less. I did not check the measurement errors - it's not very important to me.
Disadvantages I do not see it yet. Expect quality much worse. There are no lights, a lace and memory. Get round 🙂
Comment For household needs and for 600r - that's it.
Feedback about Multimeter Resant DT 830B
Advantages: Price, build quality, survivability.
Disadvantages There is no such price.
Comment It is useful to measure the voltage in the socket, and the dipper forgot to rearrange. Cut down all the machine guns, and at the multimeter only the tip of the probe melted, even the fuse did not have to be changed.
Review: Multimeter Uni-T UT33A - Home, no frills
Advantages: Compact, measurement limits are automatic
Disadvantages: there is no backlighting
Last year, I went into the Young technician, remember the youth and buy a multimeter for the house. I caught a glimpse of such a small Chinese. With the initial category A, as in the rights to a motorcycle, only from a series of four categories A, B, C and D. Absolute China of course. The tester is normal, digital, with LCD display, dialer with buzzer, diodes and transistors can be ringed, no backlighting, protection too. But it is not necessary, when measuring, for example voltage, to switch limits on this multimeter. And this often saves the device life. Styli in the set are not bad, there are even caps on them, but I have long ago thrown them out. They are inserted into the device easily, clearly there are fixed and do not drop out when measuring the necessary electrical quantities. Behind the device there is a folding plastic stand, which creates a little comfort for me when measuring this device. The device is powered by a battery of the Krone type - 9 volts. Passport instruction in an incomprehensible language is present. Maybe in retirement, still I'll read it. This device, the entry-level, is useful in everyday life, in any house, apartment and garage, for finding and eliminating the simplest faults in any home electrical and radio equipment, wiring the car and motorcycle. And the most important thing is to think a lot about what measurement limit to set, you do not have to, this device will do it automatically. I recommend to buy. The price is 600 rubles. Time of use: 2 years Price: 600 rub. General impression: Home, without any frills
The path from the arrow tester to the digital multimeter is an example of the introduction of digital technologies in measurement of the parameters of a constant and alternating electric field at a certain stage of the technical production. Without this measuring device, electricians, radio amateurs, motorists, and masters who repair electronic equipment can not do without. But the multimeter is so easy to control that home users and beginners can use it..