What is Multimeter?

 

Multimeter

A multimeter is an electronic device; Every electronic technician and engineer makes extensive use of testing equipment. A multimeter is mainly used to measure the three primary electrical properties of voltage, current and resistance. It can also be used to test the continuity between two points in an electrical circuit. This post introduces you to the basics of multimeters, applications and different types of multimeters.

The multimeter has multi-functionality as it works like ammeter, voltmeter and ohmmeter. It is a handheld device that has several positive and negative indicators on the LCD digital display. Can be used to supply multimeter batteries, household cables, electric motors and power supplies.

Applications:

Applications of ammeters are involved in various electrical and electronic projects for the testing of components and are used in various measurement applications in multimeters.

Rature temperature and environmental applications

ার Cheap weather station

এম DMM internal temperature

Voltage measurement

High and low quality DC measurement

Measures Peak and DC Average from Peak Top

• Measure current

• DC measurement

• True RMS AC

Resistance Measurement

Micro ohmmeter

Measure the resistance with constant voltage

Measure the resistance with constant current

Time Measure time and frequency

• Fast frequency

• Time measurement

 Multimeter type:

There are different types of multimeters such as analog, digital and fluke multimeters.

Digital multimeter:

Most of the multimeters we use are a digital multimeter (DMM). DMM performs all functions from AC to DC except analog. It has two probes that indicate positive and negative which are represented by black and red. The black probe is attached to the user's requirement for measuring OOM, volts or amperes with the COM jack and the red probe. The jack on the right of the figure is V and the COM jack marked with it is used for voltage, resistance and diode testing. Two jacks are used when an LCD shows what is being measured (volts, ohms, amps, etc.). Overload protection prevents damage to meters and circuits and protects the user.

Digital multimeter

A digital multimeter has an LCD, a clamp for selecting different ranges of three electronic properties, an internal circuit consisting of a signal conditioner circuit, an analog of a digital converter. PCBs connect or disconnect country rings depending on the location of the hill. Thus when the required parameters and range are selected, the PCB section is able to perform the corresponding measurement. To measure the resistance, current flows from a constant current source through an unknown resistor and the voltage across the register is amplified and fed to an analog of a digital converter and the output in the form of a resistance is displayed on a digital display. To measure an unknown AC voltage, the voltage is first switched off to get the appropriate range and then corrected to the DC signal. The analog DC signal is fed to the A / D converter to receive the DC, which indicates the RMS value of the AC signal. Similarly, to measure any AC or DC, the unknown input is first converted to a voltage signal. The digital converter is then fed to the analog to get the desired output (including correction in case of AC signal).

Analog multimeter:

The analog multimeter or VOM (volt-ohm-millimeter) scale is constructed using a moving coil meter and a pointer to indicate readings. The running coil meter consists of a coil wound around the drum placed between two permanent magnets. As the coil flows through the coil the magnetic field is induced in the coil which reacts with the magnetic field of the permanent magnets and consequently the ball reflects the pointer attached to the drum of the scale, which indicates the current reading. It also contains a fountain connected to the drum which provides an opposing force to the speed of the drum to control the removal of the pointer.

For DC measurements, the de Arsonwall movement described above can be used directly. However the full-scale deflation of the meter must be less than the current. For higher currents, the current separator rule is applied. Using different values ​​of shunt resistors, the meter can also be used to measure multi-range current. For current measurement, the instrument must be connected in series with an unknown current source.

For measuring DC voltage, a resistor is connected in series with the meter, and the meter resistance is considered in such a way that the current flowing through the registrar is equal to the current flowing through the meter and the whole reading indicates the voltage reading. For voltage measurement, the instrument must be connected in parallel with an unknown voltage source. For maltrangement measurements, different resistors of different values ​​can be used, which are connected in series with the meter.

To measure resistance, the unknown resistance is directly connected to the meter and the series across a battery, because the current flowing through the meter is directly proportional to the unknown resistance.

For measuring AC voltage or current, the same principle is applied, for measuring DC parameters the AC parameter is first corrected and filtered and the meter indicates the RMS value of the AC signal.

The advantage of analog multimeter is that it is cheap, no battery is required, can measure fluctuations in readings.

The two main factors influencing the measurement are sensitivity and accuracy. Sensitivity refers to full-scale deflection current and is measured in ohms per volt.

Fluke multimeter:

Fluke multimeters are protected against transient voltage. It is a small portable device used to measure voltage, current and test diodes. The multimeter has multiple selectors to select the desired function. Fluke MM automatically selects the maximum measurement, which means that it is not necessary to know or determine the significance of the signal in order to get the correct text; It was transferred to a suitable port suitable for the desired measurement. Protected from damage if the fuse is connected to the wrong port.