Multimeter dt 830b instructions for use. Digital Multimeter

30.07.202327.05.2017

The DT-830B multimeter is a Chinese-made device that many people use. Those who constantly deal with electronics cannot do without such equipment. This article explains what the DT-830B multimeter is. Instruction with a detailed description of the device allows you to use it even for beginners.

Many models are produced, differing in quality, accuracy and functionality.

The device is intended for the following basic measurements:

electric current values;
voltage between 2 points in an electrical circuit;
resistance.

In addition, the DT-830B multimeter and other similar models can perform many additional operations:

ring the circuit at a resistance below 50 ohms with an audible alarm;
test the semiconductor diode for integrity and determine its forward voltage;
check semiconductor transistor;
measure and inductance;
measure the temperature with a thermocouple;
determine the frequency of the harmonic signal.

How does a multimeter work?

The dial shows the measured values as numbers on a plastic or glass display.
The switch provides a change in the functions of the device, as well as switching ranges. When not in use, it is set to the "Off" position.
Sockets (connectors) in the housing for installing probes. The main thing, with the inscription COM and negative polarity, has a general purpose. A probe with a black wire is inserted into it. The next one marked VΩmA has positive polarity with a red probe.
Test flexible wires of red and black color with pincers.
Panel for transistor control.

Multimeter DT-830B: instructions with a detailed description of the measurement modes

Not everyone understands how to measure the necessary parameters with the device. When using the DT-830B multimeter, the operating instructions must be followed exactly. Otherwise, the device may burn out.

1. Resistance measurement

The function is necessary when it is required to conduct electrical wiring in the apartment or find a break in the home network. Not everyone knows how to use a multimeter in this case, but you just need to set the switch in the resistance measurement sector to the appropriate measurement range. The device has an audible alarm that the circuit is closed. If there is no signal, it means that there is a break somewhere or the resistance value of the circuit is higher than 50 ohms.

The range of minimum resistance (up to 200 ohms) is called a short circuit. If you connect the red and black probes together, the device should show a value close to zero.

The Chinese-made DT-830B multimeter has the following resistance features:

High indication error.
When measuring small resistances, the value obtained at the probe contact should be subtracted from the readings. To do this, they are pre-closed. On the other ranges of the sector, the error decreases.

2. How to measure DC voltage

The device switches to the DCV sector, divided into 5 ranges. The switch is set to a deliberately larger range of values. When measuring voltage powered by a 3 V or 12 V battery, you can set the sector to "20". You should not set it to a large value, since the reading error will increase, and at a smaller value, the device may burn out. For rough measurements, if you need an accuracy of only up to 1 V, the multimeter can be immediately set to the "500" position. The same is done when the measured voltage is unknown in magnitude. After that, you can gradually switch the range to smaller values. The highest measurement level is signaled by the "HV" warning, which lights up in the upper left corner. Large voltage values require caution in working with the device, although as a voltmeter from a DT-830B multimeter it is more reliable than an ammeter or ohmmeter.

Compliance with the polarity of the probes for a digital instrument is optional. If it does not match, this will not affect the value of the readings, and the "-" sign lights up on the left of the screen.

3. How to measure AC voltage

Installation in the ACV sector is the same as in the DCV. 220-380 V can damage the instrument if connected incorrectly.

4. DC current measurement

Small currents for electronic circuits are measured in the DCA sector. Voltage measurement is not allowed in these switch positions. In this case, a short circuit will occur.

To measure the current value up to 10 A, the third socket is used, into which the red probe should be rearranged. Readings can be taken in just a few seconds. Usually, an ammeter measures the current of electrical appliances. Use the device in this case with caution and when measurements are really needed.

5. Diode health check

In the opposite direction on the diode, the device should show infinity (one on the left). In the forward direction, the junction voltage is 400-700 mV.

In this sector, you can also check the health of the transistor. If it is presented as two back-to-back diodes, each junction must be checked for breakdown. To do this, it turns out where the base is located. For the pnp type, it is necessary to find such a conclusion (base) with the positive probe so that the negative probe shows infinity on the other two (emitter and collector). If the transistor is of type npn, the base is located by the negative probe. To find the emitter, it is necessary to measure the resistance of its transition, which is always greater than the collector. For a serviceable element, it should be in the range of 500-1200 ohms.

I drove a multimeter for quite a long time 1.5 months.

Some giblets, the smell of burning and requests for help downstairs.
ATTENTION!!! I didn’t compress photos at 80+ meters ... but photos from the phone

Background:

In the distant warm July, a kind man under the name shared his joy with the people, where you can spend a few coins. For which he is very grateful! It is not difficult for anyone to come in and also say thank you.

830 Series Differences:

The multimeter arrived in a standard yellow package:

In a beautiful box:

Package Kit:

multimeter, probes, instruction letter from the seller.

The probes are labeled 1000V, but I would be careful...

And even with a letter from the seller:

And the instruction:
I ran my eyes through the instructions, I wanted to find the characteristics of the probes, but as it turned out, there is one instruction for all types.
I liked the section on replacing the battery and fuse:
open the cover and replace the battery and fuse.
In my old DT-830, bought back in 2003, the fuse can really be removed and replaced, but here it’s not so easy.

In general, there are no questions about the parcel, only a wish that the packaging be thicker, otherwise nothing stops our mail ...

Characteristics:

screen maximum value - 1999
works from krone (9V)
Diode testing
Transistor hFE test
The manual mentions overload protection.
Calling function - nope, there is no such ...

from instructions

Switch positions are divided into sectors:
OFF/on - device power switch
DCV - DC voltage measurement (voltmeter)
ACV - measurement of alternating current voltage (voltmeter)
hFe - sector for switching on the measurement of transistors.
DCA - DC current measurement (ammeter).
10A - ammeter sector for measuring large values of direct current (according to the instructions, measurements are carried out within a few seconds).
Diode - sector for testing diodes.
Ohm - resistance measurement sector

I would like instead of diode continuity, sound continuity, and also temperature measurement, but in this model it is not. The DT-838 has.

The multimeter was taken to work for comparison with a more accurate colleague (Fluke 115). Since I myself do not deal with electronics, I asked knowledgeable people at work to check the accuracy. Before that, I disassembled it and took a picture:

viscera

These balls in the last photo are very insidious! The multimeter is disassembled in 2 minutes, and the balls are searched on the floor for 40-50 minutes and then it is simply considered that having two balls in the locking mechanism is chic!

Additional Information

Today is exactly one week since I am writing this report. I found him!

The first step was to check the voltage at the outlet. 2 probes in the lower positions in the multimeter and the other ends in the holes of the socket, and the knife switch up. BIG BAGA BOOM!))

We disassemble it again and see that a tiny strip of track near the screw burned out, it seems that the screw turned out to be a conductor))

The master (hereinafter with all due respect to the person) looked and said that now we will fix everything!
I threw the jumper directly and started testing further.

So the Master began to set the voltage on the left tester through the laboratory unit and compare it with the readings of the right (patient), all the time after the changes he muttered - “not bad, not bad”.
The Master's desk is not in disarray, I just came to him at 7:30, and we start working at 8:30. You understand that everyone rests before starting work) And I get bored with my homemade products, you know ...

The power supply on which everyone was exposed - I twisted)

Everything was “not bad, not bad” in his words, and then we moved on to resistance testing:
and then there was an ambush ... none of the provisions for checking the resistance does not work - the screen is dead. And the continuity of diodes is also deader than dead ...

We began to disassemble again and see what could be. I interfered as best I could and, at my request, they changed two resistors:

at 10 and 9.1 ohms - it did not help. We spent half a day, then I said that for now it’s enough to suffer and we need to think ...

I just felt terribly uncomfortable in front of a person that I was distracting him for 120 rubles ...

Dear experts! And now - attention, a question!
Does anyone know how to treat my patient? It's not about the money spent on it, it's about interest and passion. I saw that I was not the only one who ordered it from the muska ... perhaps someone is now sitting and giggling quietly (or a villainous laughter is heard)))

Probe resistance is approximately 0.3 ohm. It was not possible to measure the readings of the multimeter itself ...

Results:
According to the Master, the multimeter is quite accurate for its price range.
For home use, it will go for 120r then ...
Even after using it to get fire, more than half of the functions work :)

Minuses:
Runs great! (I also advised the Master to put it on the table when they climbed into 220, and not hold it in their hands)

Digital multimeters are more popular with professionals than analog multimeters, as they are more visual and easy to use. The measurement results that have been made are displayed on the liquid crystal display and displayed in the form of numbers. The risk of taking incorrect readings due to the human factor with such devices is minimal. For example, consider a digital multimeter DT-830B.

The price of such a device can be different and fluctuates depending on the functions it performs and the accuracy of the measurements. However, the function of measuring the current in the electrical network, the voltage in the network and the resistance of resistors or other devices is provided by absolutely all models, regardless of price.

All models are very similar to each other in terms of the location of the controls.

On the device in the center there is a switch with which the measurement mode and limit are selected. The parameters are divided into sectors and circled with lines for convenience.

In the upper part, as a rule, the display is located. At the bottom of the socket for connecting probes. How to use the DT-830B multimeter, consider below.

The scale shows the abbreviated designations of the measurement modes, which are better to remember, since they are not deciphered in the instructions for the DT-830B multimeter.

OFF the device is off, DCV - measure direct voltage, ACA measure alternating current, DCA measure direct current, Ω - measure resistance, ACV measure alternating voltage, hFE measure transistor parameters, ACA measure alternating current (this function is not provided in the Digital DT-830B multimeter , therefore this sector is not on the scale).

A probe is a metal rod with an insulated handle. From the measuring point, the signal is fed to the device through the drive to which the probe is connected. The probes can be modified, or made by yourself, depending on the desired length of the wires and your other preferences. A connector labeled as COM - negative, or acts as a ground.

The black wire is connected to this connector. To measure resistance, small amounts of current or voltage, a connector labeled VΩmA is provided. The inscription of the content 10A or 10 ADC indicates that this connector provides for measurements in the range of values \u200b\u200bfrom 200 mA to 10 A.

The DT-830B multimeter circuit is shown in the figure below.

Specifications of digital multimeter DT-830B:

AC voltage range: 200 V and 700 V.
DC voltage range : 200 mV; 2000mV; 20V; 200V; 1000v.
Measured resistance range 200 ohm; 2000 ohm; 20 Kom; 200 Kom; 2000 Com.
DC current range 200 µA; 2000 uA; 20 mA; 200 mA; 10 A.

The instrument can perform a diode test. It also has a function for measuring the gain of the transistor.

Using a digital device is much more convenient than an analog one. It is lightweight and small in size, not afraid of shocks and falls. Licensed models are equipped with protection against incorrect selection of the measurement mode.

For example, if the device is set to measure resistance, and the probes are mistakenly placed in a 220 V socket, it will emit a warning signal. Thanks to this, the device can be turned off before it is damaged.

Specialists whose profession is related to electrical measurements have already switched to the use of digital instruments. Their principle of operation is quite simple, similar to analog models and consists in alternately switching modes and measurement limits using the central knob, so there was no need to additionally train people to work with this device.

A digital multimeter is the main tool of a Kipovite, because with its help you can check whether the supply voltage is supplied to the sensor, measure the output current of the device, find a break in the cable, and much more. Digital multimeters are widely used due to their small size and weight, wide measurement ranges, acceptable accuracy and low price.

Unfortunately, most multimeters (especially inexpensive Chinese-made models) are equipped with only a brief instruction listing the main functions, which is why beginners often have questions about the use of these multimeters. Therefore, in this article we will consider not only the basic functions of a digital multimeter, but also how to use these functions using the example of the widely used multimeter DT 830B.

The device of the multimeter and the rules for working with it.

Simple digital multimeters such as DT 830 and similar have a 3.5-digit seven-segment LCD indicator on the front panel, a rotary switch for measurement limits and three sockets for connecting probes. The multimeter is powered by a 9V "Krona" battery. To replace the battery, it is necessary to remove the back cover of the device, which also opens access to the printed circuit board of the multimeter, on which, among other things, a 200 mA fuse is located.

One of the sockets for connecting the probes, namely the COM socket, is always used, for any kind of measurements performed. Usually a black probe is attached to the COM jack. a red probe is connected to the VΩmA socket when measuring direct and alternating voltage, resistance and direct current up to 200 mA. To measure a DC current greater than 200 mA, the red probe must be removed from the VΩmA socket and connected to the 10A socket.

On the front panel of the multimeter, there is also an eight-pin connector (socket) for connecting transistors for measuring the current gain h21e (or hFE). Moreover, it is possible to measure the current gain only for bipolar low-frequency transistors of low and medium power. Since in the process of maintenance and repair of instrumentation equipment there is no need to measure the gain of transistors, this mode of operation of the multimeter will not be considered. I can only say that the emitter of the transistor is connected to pin E of the connector, the base to pin B, and the collector to pin C, but before that it is necessary, for example, to determine the structure of the transistor from the reference book: p-n-p or n-p-n and select the appropriate side of the connector.

In the semiconductor diode continuity test mode, the multimeter generates a small test voltage and current, which is applied to the diode under test. If the diode is working, then when you connect the red probe (plus) of the multimeter to the anode, and the black probe to the cathode, the value of the voltage drop at the p-n junction of the diode will be displayed on the display. For silicon diodes, this voltage is in the range of 0.6 ... 0.9 V. With the reverse polarity of the connection (red probe - cathode, black probe - anode), the unit will be displayed on the display, since the diode conducts current in only one direction. When checking diodes without soldering them out of the circuit of the device being repaired, keep in mind that other radio components connected to the diode can distort the measurement result. Therefore, it is desirable to disconnect at least one output of the diode from the circuit.

Switching off the multimeter at the end of the measurement is carried out by setting the rotary switch to the OFF position.

When working with a multimeter, do not touch the bare part of the probes, since, firstly, this can lead to electric shock (when measuring current and voltage) and, secondly, due to the relatively low electrical resistance of the human body, the error may increase measurements, especially when measuring high resistances.

Inexpensive multimeters DT 830B and the like can only be used for measurements made when setting up equipment and troubleshooting. They cannot be used for calibration, and even more so when checking sensors and other instrumentation equipment, since the measurement accuracy of multimeter data is insufficient for these purposes and, moreover, they are not included in the state register of measuring instruments. When checking and calibrating equipment, more accurate multimeters should be used, for example, domestic B7 series instruments or imported multimeters from APPA, Fluke and the like.

Always keep an eye on the degree of discharge of the battery of the multimeter, since in the event of a strong discharge of the battery, the measurement error of the instrument increases dramatically. When buying a multimeter, give preference to those models that have a low battery indicator. And change the battery as soon as the low battery indicator lights up.

When choosing between several models of multimeters, preference should be given to those models that have wider measurement limits (or more measurement subranges) of voltage, current and resistance and a minimum measurement error. Additional functionality of devices, such as temperature measurement, capacitance, built-in pulse generator often remains unclaimed, and you should not focus on the presence of these functions when buying a multimeter.

If you do not know the value of the measured quantity, even approximately, then always start measurements by setting the maximum possible measurement limit for this type of measurement. A multimeter, especially inexpensive models, is not a repairable device (more precisely, it is cheaper to buy a new device than to repair a failed one), so when taking measurements, be careful and watch which sockets the probes are inserted into and what position the rotary switch is in.

DC and AC voltage measurement (voltmeter mode)

Let's start studying the operation of the multimeter with the voltage measurement mode (voltmeter mode), since its measurement does not require any switching or disconnection in the circuit, and technically it is most simply implemented.

First, you need to determine what voltage you are going to measure - DC or AC. To do this, carefully study the electrical circuit diagrams of this switchboard or device, marking tags and cambric on cables and wires, marking of terminals of devices and equipment and designations on the printed circuit boards of the device (if you make measurements inside the device, for example, when repairing it).

To measure DC voltage (batteries, accumulators, DC power supply outputs, power circuits of most modern instrumentation sensors, thermocouple thermoelectric power), set the rotary switch to the DCV (or V=) position. To measure AC voltage (household electrical outlet, 220V uninterruptible power supply outlets, lighting network, power supply circuits for pump motors, fans, transformers and actuators), set the rotary switch to the ACV (or V~) position.

Secondly, after you have determined the type of voltage, you must select the measurement limit. If the value of the measured voltage is not even approximately known to you (for example, a Krona battery has a constant voltage of 9V, and a household outlet has 220V AC voltage), then start measuring from the highest measurement limit, reducing the measurement limit until the measured value will be as close as possible to the measurement limit, but it will still be less than it. For example, for a DC voltage measurement, you set the limit to 200V, and when measuring voltage, you get a value of 12.0V. The resulting voltage value of 12V is less than the next 200V measurement limit of the multimeter from 0 to 20V, which means that this measurement limit can be selected. By measuring the same voltage of 12.0V at the limit of 20V, you got a more accurate voltage value of 11.98V.

And thirdly, to measure the voltage in a section of the electrical circuit, you should connect a multimeter parallel section of the circuit where the voltage is to be measured. There is no need to break or disconnect the circuit in this case.

When working with a multimeter in voltage measurement mode, remember that:

The measured voltage can be life threatening, so follow the electrical safety rules when making measurements. I recommend refreshing your knowledge of the rules and taking an electrical safety test. When measuring high voltages, the multimeter displays the HV symbols (high voltage - high voltage) warning of the risk of electric shock.
When measuring voltage, the multimeter is connected in parallel with the section of the circuit where the voltage is to be measured. In this case, to connect the multimeter, it is not necessary to break the measured circuit.
The closer the measured value is to the selected measurement limit, the more accurate the measurement result.
An ideal voltmeter has the largest possible active and reactive input resistance tending to infinity.

When measuring voltage, it is important to choose the right point relative to which the measurements are made. In AC circuits, measurements are most often performed relative to the neutral wire N, and in DC circuits - relative to the common wire, which is also often called ground, chassis, ground, GND. Moreover, in DC circuits there can be several independent and completely galvanically separated common wires, for example GNDa (analog "ground" of the analog part of the device circuit) and GNDd (digital "ground" of the digital part of the device). In this case, it is necessary to make measurements in the analog part of the device circuit relative to the analog ground GNDa, and in the digital part of the circuit - relative to the digital ground GNDd.

It should be remembered that the DT 830B multimeter is designed to measure DC voltage and AC sinusoidal voltage with a frequency of 45 to 450 Hz. Therefore, an oscilloscope should be used to measure the voltage (amplitude) of pulses, high-frequency voltage, voltage having a constant and variable component.

If you set the multimeter measurement type switch to the AC voltage measurement position and try to measure the DC voltage, the multimeter will show zero. This is due to the features of the circuitry of the digital multimeter. If you try to measure AC voltage by setting the switch to measure DC voltage, then the multimeter may fail. In addition, it is highly discouraged to measure AC voltages above 500V with a multimeter - with a high degree of probability, the device may fail.

DC Current Measurement (Ammeter Mode)

Simple multimeters type DT 830V are designed to measure only direct currents, alternating current cannot be measured with this multimeter. Therefore, preparing the multimeter for measurements comes down to selecting the desired measurement limit with the rotary switch. Measurements should be started from the highest measurement limit. Please note that when measuring currents up to 200 mA, the probes of the device must be inserted into the COM and VΩmA sockets, and when measuring currents from 200 mA to 10 A, the probe from the VΩmA socket must be moved to the 10A socket. Naturally, when measuring currents above 200 mA, the rotary switch must be set to the 10A position.

If you try to measure a larger current at the measurement limit of 200 mA, this will lead to the failure of the fuse inside the device. It is necessary to change the failed fuse for a similar high-speed fuse with a rating of 200 mA 250 V. Do not install a restored fuse (bug) instead of a blown fuse, since the multimeter itself will fail the next time the measured current is exceeded. Input 10A is not protected by a fuse. Try to measure high currents in the shortest possible time, do not leave the device connected to the measuring circuit for a long time when measuring high currents - the multimeter may fail. Some manufacturers recommend not measuring currents above 5A for more than 15 seconds.

To measure current, the multimeter in ammeter mode turns on into the gap measured circuit, in series. That is, to measure the current in the circuit, you need to break this circuit. If you connect a multimeter in current measurement mode in parallel with the circuit (like a voltmeter), then in the best case this will lead to failure of the fuse, and in the worst case of the multimeter itself.

When working with a multimeter in current measurement mode, remember that:

The magnitude of the measured current can be life-threatening, so follow the rules of electrical safety when making measurements. Do not touch the bare metal parts of the electrical circuit and the multimeter.
An ideal ammeter (multimeter in current measurement mode) has the lowest possible active and reactive input resistance tending to zero. In the event that the resistance of the ammeter is large, this resistance will be introduced into the measured circuit (since the ammeter is connected in series), which, in accordance with Ohm's law, will lead to a decrease in the current in the circuit, and obtaining unreliable readings. Due to the fact that the input resistance of the DT 830B multimeter is not equal to zero, the voltage drop across it when measuring current can reach 200 mV.

More expensive multimeters allow you to measure not only direct, but also alternating current. But in this case, to measure the current, the multimeter is included in the open circuit. In order to measure the value of the alternating current in the circuit without breaking this circuit, you can use special current clamps. Such clamps are especially convenient when measuring high alternating currents (power supply circuits for pump motors, etc.).

If during the operation of instrumentation sensors you need to frequently monitor the value of their output current, then it is best to connect these sensors to secondary circuits through special terminal blocks with disconnectors. In this case, to measure the output current of the sensor, we connect an ammeter to the input and output terminals of the block, after which we open the disconnector and measure the output current of the sensor. After the measurements are completed, put the disconnector in place and disconnect the ammeter.

In some cases, the measurement of the current in the circuit is performed by an indirect method, by measuring with a voltmeter the voltage drop across the exemplary resistance ("coil"), connected in series with the load resistance in the circuit with the measured current. So, with a reference resistance value of 1 Ohm and a current in the circuit (circuit) of 4 mA, the voltage drop across this resistance in accordance with Ohm's law will be 4 mV, and at a current of 20 mA - 20 mV. This method of measuring the output current is often used when checking or calibrating sensors and instrumentation.

Exemplary resistances can have different resistances: from hundredths of an ohm to several thousand ohms. The working position of the exemplary resistance is vertical, since oil is poured into the body of some types of exemplary resistances. A voltmeter (millivoltmeter) is connected to terminals U1 and U2 of the exemplary resistance, and terminals I1 and I2 are included in the interruption of the controlled current circuit. Keep in mind that for exemplary resistances, the maximum current that can be passed through them is regulated. The value of this current is indicated on the nameplate of the exemplary resistance or in its passport.

Electrical resistance measurement (ohmmeter mode)

An ohmmeter is used to measure the resistance of an electrical circuit, the resistance of resistors and to check the integrity of the connecting wires. The multimeter ohmmeter can only measure active resistance, the reactance of capacitances and inductances cannot be measured with an ohmmeter. Unlike current and voltage measurement modes, you can start measuring with an ohmmeter both from the smallest limit and from the largest measurement limit. Even in the event of a significant "overload", the device will not fail.

When measuring resistance, the multimeter is connected in parallel with the section of the circuit whose resistance must be determined. In this case, this circuit must be completely de-energized and no electric current must flow in it. Otherwise, the multimeter will fail.

When working with a multimeter in resistance measurement mode, remember that:

The electrical circuit whose resistance is to be measured with an ohmmeter must be completely de-energized.
The closer the measured value is to the selected measurement limit, the more accurate the measurement result. When the symbol "1" (overload) appears on the display, it is necessary to switch to a higher measurement range.
When measuring low resistances, it is necessary to take into account the resistance of the probes.
When measuring large values of resistance (MΩ - millions of ohms), a long-term setting of readings is possible - a gradual slow increase in readings to their nominal value.

The health of the ohmmeter is checked by shorting the probes to each other. In this case, the device should give readings close to zero. If, when the probes are closed, the multimeter does not show an exact zero (this may occur due to the use of non-native probes, battery discharge, etc.), it is necessary to correct the measured value by the amount of zero drift.

As a power source for a digital multimeter, it is better to use an alkaline (alkaline) nine-volt battery of the Krona type. The use of cheap salt batteries adversely affects the measurement accuracy of the multimeter, especially in more advanced models with a backlit display and when using the multimeter at low temperatures. In addition, if a dead salt battery is not changed in time, it may depressurize and the leaked electrolyte may damage the multimeter.

The most common cause of multimeter failure is setting the measurement mode rotary switch in the wrong position. This is also facilitated by the poorly readable, especially in poor visibility conditions, the pointer mark on the rotary switch. I recommend highlighting this mark with a contrasting color, for example, a drop of white paint.

Another common, but not so fatal malfunction of the multimeter is the breakage of the lead of the probes from the place of their attachment (soldering) to the probe tip. This happens due to the fact that when performing measurements, the probes often rotate about their axis, while the connecting wire remains motionless. As a result of constant twisting and untwisting, the copper core of the connecting wire breaks at the soldering point. To prevent this from happening, it is enough to fix the connecting wire relative to the probe itself, for example, using an insulating tape or a heat shrink tube, as shown in the photo.

If you still decide to replace the failed probes with new, better ones, then keep in mind that in this case, the zero of the multimeter ohmmeter may "leave" due to a change in the resistance of the probe wires.

When performing measurements with a multimeter inside instrumentation equipment with surface mounting of radio components, it is recommended to put on the probe tips pieces of PVC tubing (cambric) or heat shrink tubing. This is necessary to prevent accidental contact with the probe tip of several points of the circuit with different potentials (for example, the contact pad and the output of a nearby electronic component), as a result of which a short circuit may occur. In the case of using insulating tubes, only the very tips of the probes (their conical pointed part) are left bare.

If you have any questions about the use of digital multimeters, you can ask them in the comments at the bottom of the page. You can also test your knowledge by answering questions.

Electrical quantities cannot be seen. They can only be determined with the help of special measuring instruments. One of these devices available to everyone is a digital multimeter.

Multimeters can measure the following electrical quantities:

voltage of the power supply or between any two points of the electrical circuit;
the current consumed both by the device from the power source and by its individual elements;
resistance of elements of electrical and semiconductor devices;
capacitance of capacitors;
transistor gains;
temperature;
the frequency of the sinusoidal signal.

In addition, for the convenience of finding defects and checking the health of some semiconductor components, multimeters can:

give a sound signal if the resistance value does not exceed 50 ohms;
check the health of semiconductor diodes;
determine polarity.

Depending on the meter model, some of these functions may not be available.

Multimeter - DT830

Therefore, in order to more clearly show how to use a multimeter, let's take a specific model as a sample. It will be inexpensive multimeter DT-830.

The device of the multimeter and the purpose of the controls

The multimeter is a semiconductor device powered by batteries. Therefore, the first thing to check is their availability and performance. Before the battery is completely discharged, the device will signal this by showing the battery icon on the display.

On the instrument panel are: a display, a switch for the measured values, sockets for connecting wires (called probes), as well as connectors for testing transistors.

The display is designed to display measured values. It can also show an overload of the device (number "1") and a low battery signal.

The handle of the switch for the measured values of the DT-830 device can occupy a number of fixed positions, grouped by sectors:

"OFF" - turning off the device;
"ACV" or "V ~" - alternating voltage;
"DCA" or "A =" - direct current;
"10 A" - direct current up to 10 A inclusive;
"hFE" - parameters (serviceability) of transistors;
"diode icon" - checking the forward voltage on a semiconductor diode;
"Ω" - electrical resistance;
"DCV" or "V=" - constant voltage.

Inside the sectors ACV, DCA, DCV and Ω, the switch can take several positions, opposite which there are numbers. These figures are the measurement limits. When measuring voltages and currents, if their approximate value is not known, you must first choose the largest limit. Then, to increase accuracy, switch to a lower one until a reading of two to three significant digits is obtained.

Instrument probes are necessary for comfortable connection to the terminals of electrical appliances and their components. At the same time, they provide reliable isolation of the user from dangerous measured values.

The probes are connected to the sockets on the front panel of the device. One of them, "COM", is common to all types of measurements and is always used. The "10ADC" socket is used in the multimeter to measure the current strength at the "10 A" limit. In all other cases, the second probe is connected to the “V ΩmA” socket.

Now consider how to properly use a multimeter when measuring electrical quantities.

We measure alternating voltage

The need to measure alternating voltage arises when troubleshooting household networks, as well as electrical appliances powered by alternating current.

We connect the multimeter probes to the "COM" and "V ΩmA" jacks, the polarity of their connection does not matter. The mode switch is set to the selected measurement limit from the ACV sector.

We touch the probes with the contacts on which measurements are required, and take readings from the display.

We measure DC voltage

Measurements are made in circuits powered by direct current sources: batteries, accumulators, as well as in semiconductor devices powered by rectifiers.

The probes are also connected to the "COM" and "V ΩmA" terminals, but a black conductor is connected to the "COM". During measurements, it is connected to the negative terminal of the power source, and the red probe is connected to its plus. If the polarity is reversed, the instrument will display a "-" sign in front of the measured value.

We set the switch to the position from the “DCV” sector, while carefully choosing the measurement limit.

By changing the polarity of connecting the probes to the object under test, you can find out the polarity of its voltage at the terminals. When connecting the COM jack of the device to a point with negative polarity, the minus sign will not appear on the display.

We measure direct current

This type of measurement is used to check the amount of current drawn from batteries, accumulators or rectifiers in household or industrial equipment. Compared to the previous types of checks, it will require short-term changes to the electrical circuits.

Produces a multimeter voltage measurement between any two points without any disconnection. But the current passing through an electrical circuit element can only be measured by connecting the device in series with it.

For example, if you want to know the current consumed by a light bulb from a battery, you need to disconnect one of the power conductors. The probes from the multimeter are included in the resulting gap. In this case, polarity is observed, but in case of an error, the device will tell you about it with the same “-” sign.

If the estimated current value exceeds the uppermost measurement limit (in our case with the DT-830 it is 200 mA), then the switch position "10 A" must be used. In this case, the probe from the “V ΩmA” socket must be moved to the “10A” socket.

We measure resistance

This function is used to check the integrity of cords, cables, heating elements, and measure the resistance of resistors. And also - to search for short circuits in electrical circuits. An important note - all circuits to which the multimeter is connected at this measurement limit must be completely de-energized, otherwise the device will fail.

If you just want to check the presence or absence of contact in the circuit under test, the mode switch is moved to the position marked with the “buzzer” icon. If there is no such icon, then it is possible that the position for monitoring the health of the diodes is used for this, which should be mentioned in the instruction manual. In this case, if the resistance of the monitored circuit is less than 50 ohms, an audible signal will sound.

If it is the resistance value that is of interest, then they measure at several limits in turn, until intelligible numerical values are obtained on the display. If zeros are lit on it, then there is a short circuit between the connection points of the probes (resistance is zero). If the device shows “1” at all limits, the resistance is greater than the maximum possible that it can measure. Or a break in the circuit.

For a correct measurement of resistance, it is desirable that one of the terminals of a section of a circuit or device (resistor, diode) be disconnected from the rest of the elements. Otherwise, their own resistance will distort the test results.

Checking diodes

A feature of semiconductor diodes is the ability to conduct current in one direction, but not in the other. At the same time, the voltage at the terminals of a serviceable element does not exceed one volt. Exactly this parameter can be found in reference books, it is called "average forward voltage".

To check the health of these devices, the multimeter switches to the position with the diode icon. The black probe is connected to the "COM" terminal, the red one - "V ΩmA". Then two measurements are made on the element under test, differing in the polarity of the probes.

If you connect the red (positive) terminal to the cathode of the diode, and the black one to the anode, the device will show the value of the forward voltage. When the polarity is changed, it will show "1". If this is not the case, the diode is broken.

Checking transistors

Any transistor has a characteristic parameter - the gain. It is measured with a multimeter to check the performance of the element. For each transistor, the gain value must be selected from the reference book, this parameter is conventionally denoted as h 21E.

You will need to learn from the same directory and the location of the transistor pins. There are three of them: one is the emitter, the other is the collector, the third is the base. You will also need the type of its conductivity - p-n-p or n-p-n. Then the element is connected for testing to the multimeter socket in compliance with the pin assignment and conductivity.

We switch the multimeter switch to the “hFE” position, read the gain value from the display, compare it with the reference data. If the numbers match, the transistor is good.

MULTIMETER DT-830B
Everyone needs to know how to use measuring instruments.
Voltammeter - a universal device (shortly - "tester", from the word "test"). There are a lot of varieties. We will not consider them all. Let's take the most easily accessible Chinese-made multimeter DT-830B.

MULTIMETER DT-830B consists of:
- LCD display
-multiposition switch
- sockets for connecting probes
-panel for testing transistors
- back cover (it will be needed to replace the battery of the device, an element of the "Krona" type 9 volts)
Switch positions are divided into sectors:
OFF/on- instrument power switch
DCV- DC voltage measurement (voltmeter)
ACV- measurement of alternating current voltage (voltmeter)
hFe- sector for switching on the measurement of transistors
DCA- DC current measurement (ammeter).
10A- ammeter sector for measuring large values of direct current (according to the instructions
measurements are taken within a few seconds).
Diode-sector for testing diodes.
Ohm- resistance measurement sector.

DCV sector
On this device, the sector is divided into 5 ranges. Measurements are taken from 0 to 500 volts. We will meet a large DC voltage only when repairing a TV. This device must be handled with extreme caution at high voltages.
When turned on to the "500" volt position, the HV warning lights up on the screen in the upper left corner. that the highest level of measurement is turned on and when large values appear, you need to be extremely careful.

Typically, voltage measurement is carried out by switching large positions of the range to smaller ones if you do not know the value of the measured voltage. For example, before measuring the voltage on a cell phone or car battery, on which the maximum voltage of 3 or 12 volts is written, then boldly set the sector to the “20” volt position. If we put it on a smaller one, for example, on "2000" millivolts, the device may fail. If we put it on a large one, the readings of the device will be less accurate.
When you do not know the value of the measured voltage (of course, within the framework of household electrical equipment, where it does not exceed the values of the device), then set the "500" volts to the upper position and take a measurement. In general, roughly measuring, with an accuracy of one volt, is possible at the "500" volt position.
If greater accuracy is required, switch to the lower position only so that the measured voltage does not exceed the value at the switch position of the device. This device is convenient in measuring DC voltage in that it does not require obligatory observance of polarity. If the polarity of the probes ("+" - red, "-" - black) does not match the polarity of the measured voltage / th, the "-" sign will appear on the left side of the screen, and the value will correspond to the measured one.

ACV sector
The sector has 2 positions on this type of device - "500" and "200" volts.
Handle 220-380 volt measurements with great care.
The procedure for measuring and setting positions is similar to the DCV sector.

DCA sector.
It is a DC milliammeter and is used to measure small currents, mainly in electronic circuits. We don't need it yet.
To avoid damage to the device, do not put the switch on this sector, if you forget and start measuring the voltage, the device will fail.

In this regard, it is necessary to tell an instructive story. Being a curious child and already knowing how to ring an electrical circuit, for example, a lamp filament or an open wire, using a device, I did not distinguish between voltage and current.
I don’t remember what happened to the device that I had, but it took a “tester” to “ring out” something for a break. Asked a friend. Vasya took it from his father. A good pointer Russian C - 2 ..., I don’t remember which one, Vasya gave me. Having measured what I needed, I put the device aside and forgot about it. And I remembered when I saw that on the outlet in the wall
written 220 V 6A.
Either I wanted to make sure the accuracy of the device, or in accordance with what was written on the outlet, in short, I measured the voltage, it corresponded. Of course, the switch was on the voltage measurement, as expected. Now, without hesitation, I put the switch in position 10 and measure the current and insert the probes into the mysterious holes in the wall.
I don't remember such an explosion in my entire life. The device was torn into blackened fragments, his face was like that of a black man in the dark, his ears were covered for half an hour, it was good that there was no one at home, so he would have received it under the "full program".

So, before you try to do something, at the slightest suspicion of the presence of voltage, you need to know elementary things: what is current, voltage, resistance. You can read it on the first page of the book: http://www.eleczon.ru/step.html.

So let's move on. There is another position 10A measurement of direct current (ammeter). Measurements are made by moving the wire from the second socket to the 10 A socket. If you need to measure the current of any electrical appliance, you can use an ammeter, but again with great care. The instructions for the device say that the current measurements should be made for several seconds, but I would not recommend using this feature once again. If you read home lessons, you will find out that there are other ways to find out the approximate value of the current strength and this will be more than enough for us.

Resistance measurement sector (ohmmeter).
Divided into positions from 200 ohms to 2 megohms (2000000 ohms).
It is possible to measure resistance from 1 Ohm to 2 MΩ with the following nuances:
Firstly: the Chinese multimeter is not an accurate instrument and the error of its readings is quite large.
Secondly: unpredictable high sensitivity for accurate measurements. In this regard, when the probes are shorted together, the device indicates the resistance of the circuit, which should not be
neglect. and consider it as the resistance of the wire on the probes, i.e. when measuring small resistances, the value obtained by closing the probes must be subtracted from the result.
For example: we measure the resistance of the lamp, because. the lamp has a small resistance, set to the position of 200 ohms.
First, we will close the probes together. My device showed 0.9 ohms - which means we will subtract after measuring the resistance we need. We measure on the lamp, we get 70.8 - 0.9 \u003d 69.9 ohms.

Please note that the readings are approximate, but in our cases with household electrical appliances this
enough.
Working up the range of the sector is not difficult. If you have a unit on the left of the screen, then the resistance is greater than the set switch position, and if the unit is on the screen at the switch position of 2000KΩ, then the circuit can be considered broken.
When the numbers appear, there is some resistance in the circuit. Again, to understand the resistance values, read the first page of the book: http://www.eleczon.ru/step.html

Battery Replacement:
As soon as you notice a failure on the display, the numbers disappear or the readings do not match the approximate values, then it's time to replace the battery. Small Phillips screwdriver - back cover - new item 9 V.

Diode sector.
One position for testing diodes for breakdown (for a small
resistance) and open (infinite resistance). The principles of measurement are based on the operation of the ohmmeter. Same as hFE.

hFE sector
To measure transistors, there is a socket indicating in which socket which leg of the transistor should be placed. The transistors of both n - p - n and p - n -p conductivities are checked for breakdown, open circuit and for a greater deviation from the standard junction resistances.
Source: http://www.eleczon.ru/class.html

How to use a multimeter

This question is often asked on the forums, which is why this short guide was written. For example, the most common and cheapest Chinese multimeter for 150 rubles was taken. You should not expect accuracy from such a device, but it copes with its duties quite well.
I'll start by decoding the switch.
DCV- DC voltage measurement
ACV- AC voltage measurement
DCA- DC current measurement
hfe- measurement of transistor parameters
temp - temperature measurement, using a special sensor
Resistance measurement - Ohm icon, I don't have it on my keyboard)
On normal devices there is a sign HZ - frequency measurement, ACA - alternating current measurement,
memory of results, etc. d
We measure the DC voltage, check the battery type Krona. To do this, select the appropriate measurement limit with a switch, 20 volts in this particular case is quite suitable. For the future, if the voltage (current, resistance) is not even approximately known, we start the measurement from the maximum value, otherwise the device may fail ..

The instrument has a red and black wire. Red, as always in electrical engineering, is considered to be a plus. We include it in the positive connector of the multimeter. which is not difficult to find if you read the inscriptions near the sockets of the device.

If the polarity of the measured voltage is reversed, nothing bad will happen, just a minus will appear in front of the value on the display.

The DT-838 digital multimeter is a good option for home use. It has small size, high reliability and simple design.

Device Features

The DT-838 multimeter (or tester, as it is popularly called) allows you to perform a number of measurements:

Definition of alternating current.

DC current measurement.

Determination of current strength.

Resistance measurement.

Temperature detection (requires an additional sensor, which is purchased separately).

Carry out a sound continuity of wires.

The device operates in a wide temperature range (from 0 to plus 40 degrees). Multimeter DT-838 reflects the results of measurements on a liquid crystal display. Moreover, the device measures the indicators not once, but several times. From 3-4 readings, the device calculates the average value, which is reflected on the indicator.

The multimeter is powered by a 9-volt battery. It is included in the delivery set (most often it is already installed in the device). When determining voltage or current, the device is able to automatically determine the polarity. They are recommended to follow. If the polarities are reversed, the value will be displayed with a minus sign.

In addition to the battery, the kit includes:

Tester.

Thermocouple.

Styli.

When measuring, it is very important to connect the probes correctly. To determine the current strength, the probes are connected in series with the load. To determine other parameters, the probes are connected in series.

Working with the device

The DT-838 multimeter is easy to use. But there are situations when, after purchasing the device, people do not know how to use it. There is nothing complicated here.

The range switch is set to the desired mode. To do this, you need to choose one of the given values. The switch itself can be rotated in both directions (both clockwise and counterclockwise). One of the probes is always in the "COM" hole. For direct current, this should be "minus". The second probe is always installed in the VOMA hole. An exception is the determination of the current strength.

Voltage detection

To carry out any measurement, first you need to turn the switch that the DT-838 multimeter is equipped with to the desired mode. The instruction will help you understand which designation corresponds to the required mode.

When choosing the desired mode, you must remember that direct current is in batteries, accumulators, power supplies. On the device, it is designated DCV and is located on the left. For example, when determining the DC voltage of a battery, it is enough to set the mode to twenty volts.

Alternating current is in sockets. It is designated on the device as "AS".

The red probe must be installed in the 10ADC socket. As a rule, it is the top nest.

Additional features

Multimeter DT-838 allows you to measure temperature. To do this, change the position of the switch to the desired mode. Instead of probes, a thermocouple is connected. The tip of the suspension is connected to the object whose temperature is to be determined. In this case, a thermocouple is needed in order to measure the temperature of an object. Without it, the device will show its internal temperature. It is usually at the same level as the room temperature. This function allows you to control the heating (or overheating) of any radio components, microcircuits.

Calling connections is easy. This is necessary to determine the location of the network break (if the wiring is broken). Another possibility is to determine the resulting short circuit. To start the measurement, turn the switch to the required position. Next, two probes need to touch different ends. If a short circuit occurs, an audible signal will sound.

Home craftsmen prefer devices that combine several metrological functions. These include multimeters - devices that allow you to determine the characteristics of an electrical circuit (resistance, current and voltage). All these features are listed in the manual of the DT 830B, an inexpensive instrument that takes measurements with a high level of accuracy.

Instrument Information

The multifunction tester is available in use, is universal. The model is suitable for work at home, but it has all the features of a professional tool. The device includes measuring probes, a tool for self-diagnosis and a large scale of indicators. The multimeter receives power from a special 9 W source. The manufacturer provided only one battery in the set.

The device looks like standard testers, but has several significant differences. The data is presented in digital form, and the device itself can work with several parameters. All internal elements are enclosed in a reliable case. The central place on the surface is occupied by the switch. The main advantages of the multimeter:

performance;
portability;
ergonomics.

The device is easy to operate thanks to the massive handle with twenty positions. Around it are designations of types of work, which is useful for inexperienced users. The digital liquid crystal screen displays data on the parameter being measured.

Technical features

Household electric current meters have a fairly wide range of functions, but professional devices are more accurate and durable. The instructions for use of the DT 830 V multimeter indicate that the device has increased sensitivity. It shows accurate data, but is slightly inferior to more expensive models. Specifications:

Professional devices have a wider functionality. Many masters lack the verification option. But among the positive differences, an extended measurement scale, emergency indicators and diode testers are distinguished.

terms of Use

For the probes that are included in the kit, there are special openings on the body. Metal rods with insulated handles are required for contact between the conductor and the device. The probe is inserted into one of the three sockets, each is responsible for a certain indicator. One opening can act as negative, and common or grounded. It depends on the mode that the wizard selects for the operation of the DT 830B multimeter. Detailed instructions make it possible to correctly configure the remaining sockets.

The second VQmA port can be used to measure voltage and resistance. If the current strength exceeds 200 A, then it is necessary to immerse the probe in the third socket marked 10 ADC. As soon as contact is established between the metal rod and the element, information about the parameter will appear on the screen.

Modes and maintenance

Around the switch, the case is divided into sections that determine the mode of use of the device. Sometimes sectors allow you to accurately indicate fluctuations in measurements. The device can operate in two modes - DCV and DCA. The first makes it possible to measure the voltage of a direct electric current as a voltmeter. DCA activates ammeter mode.

The device has a section for evaluating the functionality of the diodes. To do this, insert the probes into the second and third sockets, their tips measure the resistance. If the indicator is the same in the forward and reverse directions, then the element is faulty.

The manufacturer guarantees a long service life of the multimeter, but this is also affected by the frequency of preventive maintenance. After each use, the device must be cleaned of dust and dirt. To use the multimeter DT 830B for a long time, it is necessary to diagnose it. Do not use the device in high humidity conditions, as the accuracy of the obtained parameters decreases, some elements may be damaged.

The multimeter can be transported on any vehicle, protecting it from extreme temperatures, moisture, mechanical damage and power surges. Store the device in a well-ventilated area at temperatures up to 40 degrees. Must be protected from frost, contact with alkalis, dust, acids, as all this causes corrosion.

The device is suitable for home use. This is the best option for training beginner electricians. It meets the parameters of the electrical network and household appliances. If the case or internal parts are damaged, you need to contact a specialist; you can disassemble the multimeter yourself only if you have experience working with such devices.

Modern measuring devices have long reached a new level - digital technologies have firmly occupied almost all positions, displacing outdated analog devices. To a large extent, this also affected such common measuring instruments as a voltmeter and an ammeter. Now, in a small convenient case, a device fits, which allows you to measure with high accuracy both the main parameters - current strength, resistance, voltage, and many others - frequency, capacitance, temperature, etc.

And this multifunctional device is called a digital multimeter. Why you need it, how to choose and use this device correctly, we will tell further.

How to choose the right multimeter

The most common models of these digital measuring instruments are:

digital tester DT-830 .. DT-838 and their analogues M-830 - M-838;
Mastech MY-61 .. MY-68;
current clamp UT 201 .. UT 207;
MS-8205;
DT 9202 .. DT 9208.

Modern digital devices provide a lot of opportunities. The main parameters and measurement modes for all models of these devices are the same - they are all capable of determining voltage, current and resistance.

Each model also includes one or more additional features:

chain continuity with audible signal,
diode test,
definition of inductance,
capacitor capacitance measurement (models MY-63, MY-65, MY-68, UT-70C, DT-9202A, DT-9208A)
signal frequency detection (MY-63, My-65, MY-68, DT-830A, DT-832, DT-832H, UT-70C)
devices with temperature measurement (DT-830BL, DT-837, DT-838, М-838),
checking and determining the parameters of transistors (models MY-68, MY-65, MY-67, MY-63, DT-182, DT-830B, DT-832, DT-832H, DT-838),
multimeters with current clamps (MY-68, UT-201/202/204/205/207/208, 266 series instruments).

In addition, there are models of these digital devices with an oscilloscope, an RS-232 connector (communication with a computer), a built-in signal generator, and other unique features.

The choice of a digital meter for the home is determined primarily by the parameters that need to be controlled

Those. It doesn't make sense to buy a professional digital meter with a built-in oscilloscope if you're choosing a device to use in the garage to determine the state of charge of the battery. Devices that measure frequency or transistor parameters are also rarely needed for measurements, unless you are doing it professionally.

Therefore, due to their versatility, acceptable parameters, good quality and low cost, testers of the DT-830 .. and Mastech MY-61 .. series are most widely used.

How to choose the right digital meter, the following video will tell you:

How to use these measuring devices

Devices of this type are among those products, the misuse of which in most cases leads to their failure. And given that they are practically unrepairable, then you should work with the device carefully, having studied the instructions and having at least basic knowledge of electrical measurements.

How to use the most common multimeter DT 830B

Working with this model involves the following types of measurements:

Current measurement: this device allows you to measure only direct current. To do this, the probes included in the “COM” and “VΩmA” sockets are connected to the circuit in series with the load. At a current of more than 0.2 A, the “VΩmA” probe is switched to the “10A” socket. Set the limit switch to the required position.
To measure alternating current, you must use the device type DT-9202A/9208A.
Measurement by the device of current strength over 10A is not provided. For these purposes, use a model with clamp meters, for example, the Mastech MY-68 model.
Voltage measurement: The device can measure DC and AC voltage values. To do this, the probes are connected to the “COM” and “VΩmA” jacks, and the switch selects the type of voltage DCV - constant, ACV - variable, and the required limit.
How to determine the polarity of the voltage: When connecting the black probe to the “COM” connector, the red one to “VΩmA”, and the other ends to the “minus” and “plus”, respectively, the readings on the instrument indicator will be without the “-” (minus) sign
Resistance measurement: the switch is placed in the “Ω” position to the required measurement limit. The DT-830B meter allows you to control this parameter within 200 Ohm - 2MΩ with an accuracy of 1%
How to use the DT-832, DT-838 and other testers in this series: just like the 830
Multimeters M-830 .. M-838 are complete analogues of the devices described above. In addition, M 838 is equipped with a thermocouple for measuring temperatures in the range of 20 .. 300 degrees C

Description of digital devices and work with the multimeter are detailed in the instruction manual, manuals for the most common of them can be downloaded from the links below.

DT Series

Digital multimeter DT-830B (A-D), DT-832, DT-837, DT-838
DT-9205A, DT-9202
M-832, M-838
Instructions for working with the device M-890
DT-83B
DT-181, DT-182
DT-700B,C,D
DT-33 instruction manual
Current Clamps M-266 C, 266 F, 266FT - user manual