What is a Multimeter?
An electronic device called a multimeter is used to measure circuit resistance, amps, and voltage. Engineers can use multimeters to check voltage, resistance, and electrical current levels by connecting two leads to various electrical system components.
This device is also sometimes referred to as a volt-ohm metre or volt-ohm-milliampere (VOM).
The multimeter can work as an ammeter, voltmeter, and ohmmeter, among other things. It is a portable device with positive and negative indication needles above an LCD digital display with numbers. Electric motors, home wiring, batteries, and power sources can all be tested with multimeters.
Construction of Multimeter:
Components of Multimeter include
- A display,
- A power source,
- Probes, and
Both analogue and digital multimeters perform and operate in much the same way. This device has three ports and two leads, a red and a black probe. The red colour leads are used to plug into specific ports as needed, while the black colour leads are used to plug into the common port.
Working of Multimeter:
The instrument’s centre knob can be turned ON once the leads have been connected in to perform the proper function for the particular component test.
Ex: The multimeter will detect DC voltage up to 20V after the knob is set to 20V DC. Set the knob on the multimeter to the 2V/200mV range to compute low voltages.
The ends of each probe must be touched to the terminal ends of the components in order to get a reading from the meters. In order to give current or voltage that does not exceed the highest rating of the meters, many multimeter devices are highly safe to use on devices and circuits. Depending on the type, these instruments are able to produce a variety of readings. Therefore, the most common uses for basic types of multimeters include measuring amperage, resistance, voltage, and checking for continuity. A complete circuit can also be examined as shown below.
- Ohms of resistance
- Volume in Farads
- The Celsius/Fahrenheit temperature
- Voltage & Amperage in AC
- Inductance Henrys
- DC Voltage and Amps
- Frequency in Hertz
- Conductance in Siemens
- Task Cycle
Some multimeter types allow the attachment of special sensors or accessories for additional readings such as acidity, light level, alkalinity, wind speed, and relative humidity.
Types of Multimeter:
There are 2 different types of multimeters includes:
- Analog multimeter,
- Digital Multimeter.
AC: A moving coil metre is used in the construction of the analogue multimeter, also known as the VOM (Volt-Ohm-Milliammeter), together with a pointer to show the reading on the scale. A coil that is looped around a drum and positioned between two permanent magnets makes up the moving coil metre.
The magnetic field of the permanent magnets reacts with the magnetic field of the coil when current flows through it, creating a force that causes the pointer linked to the drum to deflect on the scale, giving the current reading. In order to manage the deflection of the pointer, it additionally comprises of springs attached to the drum, which exert an opposing force on the drum’s motion.
DC: The current to be measured for DC should have a lower value than the meter’s full-scale deflection current. The current divider rule is employed for higher currents. The metre can also be used to measure current in many ranges by using various quantities of shunt resistors. The device must be linked in series with the unidentified current source in order to measure current.
Advantages of Analog Multimeter:
An analogue multimeter has the benefits of being affordable, not requiring a battery, and being able to measure reading fluctuations.
Disadvantages of Analog Multimeter:
Sensitivity and accuracy are the two key elements that affect the measurement. The unit of measurement for sensitivity is ohms per volt and refers to the reciprocal of the full-scale deflection current.
The internal circuitry of the digital multimeter comprises of a signal conditioning circuitry, an analogue to digital converter, an LCD, a knob to select different ranges of the three electrical characteristics, and other components. Depending on where the knob is positioned, concentric rings on the PCB are either connected or detached. The part of the PCB is triggered to carry out the corresponding measurement as soon as the required parameter and the range are chosen.
In order to measure resistance, current is passed through an unknown resistor from a constant current source. The voltage across the resistor is then amplified and fed to an analogue to digital converter, where the output, which takes the form of resistance, is then displayed on the digital display.
To measure an unknown AC voltage, the voltage is first attenuated to obtain an appropriate range, rectified to DC signal, and then given to an A/D converter as an analogue DC signal to produce a display that shows the RMS value of the AC signal.
Advantages of Digital Multimeter:
- Digital Multimeter displays an automatic o/p screen.
- The meter’s measurement results can be recorded, stored in memory, and synchronised through a PC.
- It has auto polarity features.
- The battery’s ability to charge cannot affect how accurately the metre reads.
- It guarantees accuracy
- A protection against mechanical harm.
- There can be no modifications needed at zero.
- High measurement accuracy
- The choice of measuring ranges can be made manually or automatically.
Disadvantages of Digital Multimeter:
- It is more expensive than analogue.
- Due to measurement fluctuations, this multimeter does not function properly.
Application of Multimeter:
The following are some of the uses for multimeters.
- Voltage measurement for AC/DC
- Measurement of AC/DC current
- Measurement of resistance & continuity
- Check the diode
- Calculating capacitance
- Determining frequency
- Battery testing
- It is utilised in environmental and temperature applications
- It’s possible to identify a damaged power cable.
- To test the switch.
- The ability to test an outlet
- Tests can be performed onincandescent light bulbs.
- Time and frequency measurement
What is the function of Multimeter in IT?
Modern digital multimeters are capable of measuring incredibly minute variations or fluctuations. Although some multimeters test wider voltage ranges, experts point out that it will be harder to spot tiny changes in these higher ranges.
In the field oftechnology, multimeters are quite useful. Professionals may use a multimeter during hardware troubleshooting to determine whether certain hardware devices are receiving enough current or whether anything has changed in an existing configuration. The multimeter, which is often associated with home or commercial electricians, can also be used by specialists to identify problems with the energy supplies that power sophisticated data systems.