From this article, you can find out what the electric multimeter is: a tester with which you can measure current, direct and alternating voltage and resistance. Let us consider which devices have additional functions, such as measuring the gain of a transistor, testing diodes, continuity of an electrical circuit, measuring the frequency of an electrical signal, temperature, parameters of capacitors, inductance of coils.
Electrical multimeter: tester for measuring electrical characteristics
To measure electrical parameters, universal multimeters (testers), current clamp DT 266, which is a portable compact model of the device, are often used. All multimeters have a similar design with the exception of some distinctive features. A typical tester consists of:
- LCD display;
- rotary switch measurement modes;
- three connectors for connecting probes;
- jacks for connecting the transistor;
- on / off buttons
On the case of a digital multimeter (tester) there is a scale of designations of measured values and their maximum values. By turning the switch you can choose one of them:
- DCV – measuring DC voltage;
- ACV – measurement of alternating voltage;
- ? – measurement of resistance;
- DCA – DC measurement;
- HFE – measurement of the parameters of the transistor;
- diode sign – check or dialing diodes
The device is equipped with several sockets for connecting red and black probes. Probes are included in the kit, but often are elements of low quality. If they fail, you can make probes for a multimeter with your own hands, for example, from pen cases and dart tips. To measure the values you need to connect them correctly, otherwise you can disable the multimeter. The black probe should be connected to the COM socket, and the red one should be connected to the 10A connector for measuring the current above 200 mA, and to the VA?
Before measuring electrical quantities, check the instrument. It is necessary in parallel with another tester or voltmeter to connect to the outlet and verify the readings. To check the accuracy of the resistance measurement, you should take the device marked with and compare it with the tester reading. To verify the accuracy of the measurement of the current, it is worthwhile to carry out alternate measurements of the same load with this device and ammeter.
On the example of the DT 832 multimeter, the instruction manual of which contains a detailed description of all the manipulations with the device, we consider the main operating modes of the device.
The resistance scale can be used for such purposes as piercing a transformer with a multimeter, determining the resistance of a resistor, identifying faulty elements, showing low voltage, reverse resistance of diodes, resistance of a heating element.
To measure the resistance, you need to set the rotary switch to the appropriate sector? If the approximate value is unknown, the switch is set to the smallest value, which corresponds to 200 ohms. If the display shows “1”, this indicates that the resistance is greater, so you must go to the next level. Make measurements until correct information is obtained.
Note! It should be remembered that before measuring the resistance, it is necessary to make sure that there is no power on the network. Otherwise, the device will produce false values.
To measure an alternating voltage, it is necessary to direct the switch to the V ~ or ACV sector, which consists of two positions of 200 V and 750 V. Measurements start from a larger value. If the result was small, then for a more accurate measurement it is worth moving to a low position. The black probe is connected to the COM connector, and the red probe is in VA ?. When measuring this indicator, compliance with polarity is optional.
To measure the DC voltage, the multimeter switch is set to the V or DCV sector, where the scale is divided into 5 ranges. Measurement should begin with the highest value of 1000 V, and gradually lower it until the correct result is obtained. If you do not follow this rule, the device may fail.
Measurement of direct current should be carried out with extreme caution and accuracy. To do this, set the switch to the desired DCA sector. Now it is necessary to attach the probes correctly. Black is still inserted into the COM connector, and red should be installed in VA ?, when the estimated current value does not exceed 200 mA. If the current is higher than this indicator, then the probe is set to 10A. If you confuse the situation, you can burn a multimeter.
One should start measuring the current with a multimeter from the maximum value of the measurement threshold, gradually lowering it until the required value is obtained.
Important! To measure current, the multimeter should be connected to the circuit in series, and for resistance and voltage – in parallel.
Temperature measurement by a multimeter is performed using a thermocouple, which is connected to the device instead of the probes.
When working with electrical equipment, it is sometimes necessary to determine the inductance. Finding a tester with this feature is quite difficult. For this you need to use a special prefix. As such an element for measuring inductance with a multimeter, a digital tester will be suitable, having a voltage measurement accuracy threshold of 200 mV.
When it is necessary to determine the operability of the equipment or the health of the wiring, the first thing to do is to ring the cable and wire with a tester. It will immediately reveal a possible break in the circuit, its resistance and the presence of a short circuit.
Helpful advice! It is not necessary to use a model with this function for wire dialing. For this, an inexpensive multimeter with minimal capabilities is suitable.
First you need to set the switch to the diode icon. The red probe should be installed in the connector ?, black – COM. Further, to check the device, it is necessary to connect the ends of the test leads to each other. Must ring a distinctive signal. Now you can proceed to the dialing of the wire. To do this, the probes need to touch the bare cable or wire. The integrity of the wire indicates a beep. In this case, the screen displays the value of resistance or “0”. If there is no sound signal, and the value “1” is displayed, then the wire to be tested is broken.
Next, we consider how to ring a multimeter stranded cable. To do this, each end should be cleaned and divided into wires. Now you need to check for a short circuit in each core. Here the sound signal symbolizes the presence of a short circuit between the conductors. This is especially important when working with high voltages.
Now you need to check the integrity of all lived. The conductors of one end of the cable are twisted together, and at the other end each is checked by the instrument. If the audio signal is missing at least once, the integrity of the conductor is broken.
The most common cause of damage to electronic equipment is the failure of capacitors, which are part of the board. To identify a weak link, you need to ring each of them with a multimeter.
Before checking the capacitor capacity with a multimeter, it is necessary to completely discharge it, otherwise it may damage the measuring device. To discharge a low-voltage device, it is necessary to short the terminals, and for a high-voltage capacitor with a large capacitance, use a 5-10 kΩ resistor, which is connected to the device.
A serviceable capacitor has a capacity of at least 0.25 microfarad. Before checking the capacitance of a capacitor with a multimeter, set the device to the appropriate measurement mode at the required limit. If the tester is equipped with special fit sockets, insert a capacitor in them.
How to check a capacitor with a multimeter without unsoldering it from the board? To do this, you must attach them to the measuring device and touch the terminals of the capacitor. Here it is necessary to strictly observe the polarity. Otherwise, the device will immediately fail. On the screen of the multimeter displays the value of the capacitance, which should be close to nominal. If not, the capacitor is faulty.
Important! It should be remembered that manufacturers of capacitors always tick the negative contact on the device.
How to ring a capacitor with a multimeter if there is no function to measure its capacitance? To do this, you must transfer the device to the resistance measurement mode and touch the probes to the appropriate polarity of the leads. The tester displays the value that will increase. This is due to the fact that the multimeter, in contact with the capacitor, charges it. After some time, the screen displays “1”, which indicates that the device is in good condition.
If at the beginning of the test the figure “1” appeared on the screen, it means that there was a break in the capacitor and it is already faulty. If “0” appears, a short circuit has occurred inside the device.
A more detailed course of measurements can be viewed on the video – how to check a capacitor with a multimeter.
Multimeter: which is better to choose a device for use at home
Characteristics of the device. Varieties of testers. How to use the device. Rating of the most popular models.
A resistor is an electronic element with a variable or specific electrical resistance value. Before you call the resistor with a multimeter, it is necessary to visually inspect it for the presence of chips and cracks on the device case. If there is no visible damage, then proceed to check the item. To do this, it is necessary to use the concept, on the basis of which measurements are made at test points, where the required values of quantities are indicated.
The most common way to test a multimeter with a resistor is to measure the resistance, which should be close to nominal. To do this, switch the tester to the appropriate position. The red probe is connected to the V? MA connector, and the black one is COM.
Before you call the resistor, it is necessary to identify the good condition of its wires. They are closed between themselves. The device should display “0”. Now you can go to measure the resistance of the resistor. If the display shows “1”, the resistor is faulty. If another value is displayed, it is compared with the nominal value, taking into account the tolerance. The resistor is good if the values match.
How to check with a multimeter a resistor without soldering it from the board? To do this, you can use the ping mode. If the item is in good condition, a characteristic signal will sound.
With the help of a tester, it is possible to diagnose many elements of electrical appliances and thereby identify a fault.
Before you call the TEN multimeter, you should find out its resistance, which will be compared with the tester’s reading. To do this, you must use the formula R = U2 / P, where U is the applied voltage, P is the power, which is indicated on the instrument case.
To measure, set the switch to the required range for measuring resistance. Multimeter probes attach to the body of the household appliance and to the output contacts of the heater in turn. If the display shows a value close to that obtained from the formula, then the heater is operational. The value “0” indicates a short circuit inside the helix, and an infinite value or “1” indicates that the helix is broken.
Often the question arises: how to ring a household appliance with a multimeter? Since there are several engine types, the unit will be tested differently.
Before checking the motor with a multimeter, it is necessary to make an external examination of it, to touch the metal surfaces with your hands.
Before checking it is necessary to completely de-energize the device. Set the tester in ohmmeter mode by switching to the maximum measurement range. How to work as a multimeter, the video in the article clearly displays the sequence of measurements to check the performance of the engine.
Today, many lighting fixtures are equipped with progressive light sources, such as LEDs, which may intermittently fail. It is then that an important task arises, how to check the LED with a multimeter. To do this, you need to use a tester with a dial tone mode, in which the performance of the diodes is checked. Here it is necessary to strictly observe the polarity of the LED.
The red probe of the device is connected to the anode, and the black one to the cathode. If everything is done correctly, the working LED should turn on. However, it should be borne in mind that when working in the dialing mode, the multimeter has a low current indicator, so the diode may not respond. Here you should reduce the lighting in order to clearly see the diode glow. Also, the displayed value on the tester display, which differs from 1, indicates that the item is in good condition.
Helpful advice! Here you can simultaneously check the power of the LED with a multimeter by calculating this parameter based on the results obtained.
Using a tester, you can identify two defects in the operation of a simple voltage and current converter. Before you check a transformer with a multimeter, you need to know the findings of all its windings. Then, using a measuring device, ring each winding of the device in ohmmeter mode. If 1 is displayed on the tester’s screen, this indicates a winding break.
To detect a short circuit, one tester probe should touch the winding pin, and the other alternately connect to the leads of the other windings and the housing. Short circuit should not be here.
Rechargeable batteries are used to accumulate and supply consumers with electrical energy during off-line operation. Using a multimeter, you can check the operating voltage, operating current, internal resistance, EMF and leakage current of the battery. The most common question is how to check the battery charge with a multimeter.
To do this, you must ensure that the battery is fully charged. Further, with the help of a powerful consumer, the load on the battery is created by connecting in series the battery, the tester and the consumer. Current is measured. Periodically it is necessary to make measurements of the battery voltage. As soon as this value starts to decrease, the start time of the battery discharge is fixed. Now the total time that has passed since the beginning of the test is multiplied by the load current. The resulting value corresponds to the battery capacity.
The result obtained after checking the battery with a multimeter should be compared with the passport data. If the value is below the nominal, the device is not suitable for further work.
When using many household appliances, some users are interested in how to check the capacity of a 18650 battery with a multimeter. First you need to know the nominal capacity of the element, the value of which is usually written on the case.
Considering the question of how to measure the battery capacity with a multimeter, you need to understand the process technology. The measuring device is switched to the measurement mode of direct current in the range of 10 MA. Further, the red probe is supplied to the positive terminal of the battery, and the black one to the negative terminal. The screen should display a value that is close to nominal. Then the item is suitable for further work.
After we checked the battery capacity with a multimeter, using the obtained value on the device, we can talk about the further fate of the element. If the result is slightly lower than the nominal, the battery can be used for more powerful equipment, for example, for a clock, a flashlight. If the value is close to 1 A, the item is useful to ensure the operability of the remote control.
If there is a question about how to check the phone’s battery capacity with a multimeter, remember that the tester will show only an approximate value. For a more accurate diagnosis, you should use a computer program or a special charger.
Many car owners often wonder: how to check a car battery with a multimeter when the engine is running? To do this, the tester is transferred to the voltage measurement mode. Observing the polarity, the measuring device is connected to the battery. If the display shows a value of 13.5-14 V, this indicates the normal operating status of the power supply. If the value is above 14.2 V, this is a sign of low charge.
We now turn to the question of how to check the charge on a non-working engine with a multimeter. The principle of measurement remains the same as when the engine is running. Normal operation of the battery should correspond to the obtained value, which is in the range of 12.5-13 V. If the value is below 12 V, it means that the unit is completely discharged.
One of the important parts of any car is DFID. How to check a flowmeter with a multimeter is described below. To do this, you need to understand the design of the sensor and clearly follow the instructions.
To check the performance of the mass air flow sensor, it is not necessary to use the services of a car service center. Saving money and time, you can check the DMRV multimeter. First you need to know the pinout of the contact group. Remove the sensor from the installation site is not necessary.
The tester is set to measure DC to 2 V. Checking the DMRV sensor with a multimeter is performed in a clear sequence. The red probe touches the yellow wire, which is responsible for supplying the incoming signal from the computer. The black probe connects to the green wire responsible for grounding. Turning the ignition key, do not start the car, you need to look at the instrument readings.
The DMRV test of the VAZ-2114 with a multimeter was successful if the device display shows a value of no more than 1.02 V. The sensor does not work if the tester displays a reading greater than 1.05 V.
Note! In order to check the DMRV multimeter on the VAZ 2110, how it works, you must perform all the above steps.
Before checking the camshaft sensor with a multimeter, you must turn off the ignition. Next, disconnect all wires from the device. Put the tester in the voltage measurement mode. Connect the mass of the tester to the engine mass. The measurement result must correspond to the voltage characteristic of the battery terminals. If the readings are different, the device’s power supply circuit has failed. Then, in a similar way, you should measure the voltage on the mass of the sensor. It must be 0.
Now connect one wire of the multimeter to the strong output of the sensor, and the other to the input of the control system. Scroll through the starter motor. If the screen displays 0.4-5 V, the sensor is working.
How to check with a multimeter knock sensor? The device is set to the position of measuring voltage at 200 MV. Probes join the contacts. Now you should beat a solid object on the device. If the device, depending on the impact, the voltage reading increases to 40 MB, the sensor is faulty.
Next, consider how to ring a multimeter ignition coil. First you need to make sure that the primary winding is in good condition. To do this, set the device to the resistance measurement mode and connect the probes to the “+” and “-” contacts. If the screen displays a value in the range of 0.4-2 Ohms, the coil is healthy. The digit 0 indicates a short circuit. If infinity is displayed, an open circuit has occurred.
The second stage of the decision of a question how to check the ignition coil with a multimeter is ringing the secondary winding of the device. For this, it is necessary to connect the multimeter probes to the output from the high voltage wire and to the “+” contact. If the coil is equipped with a plate-type core, the resistance will be 6-8 kΩ, another type – 15 kΩ.
A more detailed course of the measurements can be found in the video “How to check the ignition coil with a multimeter”.
The efficiency of the car’s ignition system is ensured by two devices that work in pairs: a generator and a rechargeable battery. Violation of the normal working condition of one of them will lead to a decrease in the efficiency of the entire unit.
Before you check the generator with a multimeter, you should perform an external inspection. Then you should start testing the relay-regulator, which maintains the constant voltage of the car. For this, the tester is set to the constant voltage mode in the range of 50 V. With the help of the probes of the corresponding polarity, the voltage at the input terminals of the generator is measured. It should be in the range of 14-14,2 V.
If the fault is not detected, you should go to the question of how to check the diode bridge with a multimeter. To do this, it is necessary to disassemble the generator case and check it.
If the diode bridge is in good condition, check the generator rotor. To do this, put the tester into the resistance measurement mode and check it on the collector rings of the field winding. The value should not be too big.
Helpful advice! If a short circuit or an open circuit is detected during the measurement, you should contact a specialist.
The last step is to perform dialing with a stator multimeter for the absence of a short circuit of the windings. Resistance on the instrument should be close to 1.
In electronics, diode bridges are often used in the same package. You can find out their performance or detect damage using a conventional tester.
Before you ring the diode bridge, the multimeter is set to the test mode of the diode or dialing. Verification is carried out directly. The red probe connects to the negative terminal and the black probe to the output labeled AC. This is how the threshold voltage is measured, which for silicon diodes is 400-1000 mV.
Helpful advice! In order to be 100% sure that the diode bridge is in good condition, the test occurs in the reverse connection. The black probe connects to the negative terminal, and the red one connects to the positive terminal. The value “1” should be displayed on the screen of the multimeter. This suggests that there is a high resistance in the P-N junction, and the diodes do not pass current.
In this way all diodes of the bridge are checked. If during the dialing of the diodes a zero resistance appears on the display of the multimeter or the device beeps, this indicates a broken element inside the diode bridge. When checking in reverse power on the screen also displays “1”. However, if a unit is displayed on the display of the device when it is turned on and off, this indicates a breakage when the diode does not conduct current.
Before using a measuring device, it is necessary to study in detail the instruction “How to use a multimeter”, where all possible manipulations with the tester are described in detail. Strictly following the recommendations, you can take all the necessary measurements that do not disable the device and make it work safe.