Multimeter Types and Their Applications

Most of the engineers, as well as technicians in the electronics field, know the measurement device namely a multimeter. Multimeters are available in different forms in the market based on the characteristics. A multimeter is an essential measurement instrument, used in any engineering workshop or any lab. The main function of this device is to measure the electrical properties of tools as well as wiring in industries. At present, multimeters are used for different purposes based on the requirements like to deal with electricity, laboratories, power sources & circuits. The different electrical parameters in the multimeter can be selected using a dial or a rotary switch on the front side of the instrument. This article discusses an overview of multimeter types.

What is a Multimeter?

A Multimeter is an electronic instrument, every electronic technician and engineer’s widely used piece of test equipment. A multimeter is mainly used to measure the three basic electrical characteristics of voltage, current, and resistance. It can also be used to test continuity between two points in an electrical circuit. This post mainly introduces the basic information of multimeters, applications, and types of multimeters are in. Let’s see all of these.

The multimeter has multi functionalities like, acts like ammeter, voltmeter, and ohmmeter. It is a handheld device with positive and negative indicator needles over a numeric LCD digital display. Multimeters can be used for testing batteries, household wiring, electric motors, and power supplies.

The essential parts of the multimeter mainly include a display, power source, probes, and controls.

How to use a Multimeter?

The function and operation of a multimeter are similar for both analog and digital types. This instrument includes two leads or probes namely red and black & three ports. The black color lead is used to plug into the common port, whereas the red color leads plug into other ports based on the requirement.

Once the leads are plugged in, the knob can be switched ON in the center of the instrument so that the appropriate function can be done for the specific component test. For instance, once the knob is situated to 20V DC, then the multimeter will notice DC voltage up to 20V. To calculate low voltages, then set the knob in the multimeter to the 2V/200mV range.

To obtain a reading from the meter, you need to touch the end of each probe to the end of the terminals of components. Types of multimeter devices are very safe to utilize on devices and circuits to provide the current or voltage that does not go above the highest rating of the meter.

While measuring, we must be very cautious so don’t touch the bar ends of the metal in the tester when activated otherwise you will get an electrical shock.

Functions of Multimeters

These instruments are capable of different readings based on the model. So basic types of multimeter are mainly used to measure amperage, resistance, voltage, checks continuity and a complete circuit can be tested like the following.

• Resistance in Ohms
• Capacity in Farads
• The temperature in Fahrenheit/ Celsius
• AC Voltage & Amperage
• Inductance Henrys
• DC Voltage & Amperage
• Frequency in Hz
• Conductance in Siemens
• Decibels
• Duty Cycle

To some types of multimeters, special sensors or accessories can be attached for extra readings like acidity, light level, alkalinity, wind speed & relative humidity.

Types of Multimeter

There are different types of multimeters like Analog, Digital, and Fluke multimeters.

Analog Multimeter

The Analog Multimeter or VOM (Volt-Ohm-Milliammeter) is constructed using a moving coil meter and a pointer to indicate the reading on the scale. The moving coil meter consists of a coil wound around a drum placed between two permanent magnets.

As current passes through the coil, the magnetic field is induced in the coil which reacts with the magnetic field of the permanent magnets and the resultant force causes the pointer attached to the drum to deflect on the scale, indicating the current reading. It also consists of springs attached to the drum which provides an opposing force to the motion of the drum to control the deflection of the pointer.

For the measurement of DC, the D Arsonval movement described above can be directly used. However, the current to be measured should be lesser than the full-scale deflection current of the meter. For higher currents, the current divider rule is applied. Using different values of shunt resistors, the meter can also be used for multi-range current measurements. For current measurement, the instrument is to be connected in series with the unknown current source.

For measurement of DC voltage, a resistor is connected in series with the meter, and the meter resistance is taken into account such that the current passing through the resistor is the same as the current passing through the meter and the whole reading indicates the voltage reading. For voltage measurement, the instrument is to be connected in parallel with the unknown voltage source. For multirange measurement, different resistors of different values can be used, which are connected in series with the meter.

For measurement of resistance, the unknown resistance is connected in series with the meter and across a battery, such that the current passing through the meter is directly proportional to the unknown resistance. For AC voltage or current measurement, the same principle is applied, except for the fact that the AC parameter to be measured is first rectified and filtered to get the DC parameter and the meter indicates the RMS value of the AC signal.

Advantages of an Analog Multimeter are that it is inexpensive, doesn’t require a battery, can measure fluctuations in the readings. The two main factors affecting the measurement are sensitivity and accuracy. Sensitivity refers to the reciprocal of the full-scale deflection current and is measured in ohms per volt.

Digital Multimeters

We mostly used a multimeter is a digital multimeter (DMM). The DMM performs all functions from AC to DC other than analog. It has two probes positive and negative indicated with black and red color is shown in the figure. The black probe connected to COM JACK and the red probe connected by user requirement to measure ohm, volt, or amperes.

The jack marked VΩ and the COM jack on the right of the picture are used for measuring voltages, resistance, and for testing a diode. The two jacks are utilized when an LCD shows what is being measured (volts, ohms, amps, etc.). Overload protection prevents damage to the meter and the circuit and protects the user.

The Digital Multimeter consists of an LCD, a knob to select various ranges of the three electrical characteristics, an internal circuitry consisting of a signal conditioning circuitry, an analog to digital converter. The PCB consists of concentric rings that are connected or disconnected based on the position of the knob. Thus as the required parameter and the range are selected, the section of the PCB is activated to perform the corresponding measurement.

To measure the resistance, current flows from a constant current source through the unknown resistor, and the voltage across the resistor are amplified and fed to an Analog to Digital Converter and the resultant output in form of resistance is displayed on the digital display. To measure an unknown AC voltage, the voltage is first attenuated to get the suitable range and then rectified to DC signal and the analog DC signal is fed to an A/D converter to get the display, which indicates the RMS value of the AC signal.

Similarly to measure an AC or DC, the unknown input is first converted to a voltage signal and then fed to an analog to digital converter to get the desired output(with rectification in case of AC signal). Advantages of a  Digital Multimeter are its output display which directly shows the measured value,  high accuracy, ability to read both positive and negative values.

Types of Digital Multimeter

Digital types of multimeter are available in three types.

Fluke Multimeter

The fluke digital multimeter can be designed with various collaboration functions. Generally, it includes a large display and this instrument is used to measure the voltage as well as electrical resistance. Some kinds of devices are available with advanced features to measure humidity, duty cycle, pressure, frequency temperature, etc. The fluke multimeter is one of the most frequently and famous instruments.
This kind of multimeter is mainly used for calibration efforts and used to calibrate currents, volts & other electrical units.

The fluke multimeters are protected against the transient voltage. It is a small portable device used to measure voltage, current, and test diodes. The multimeter has multi selectors to select the desired function. The fluke MM automatically ranges to select most measurements. This means the magnitude of the signal does not have to be known or determined to take an accurate reading, it directly moved to the appropriate port for the desired measurement. The fuse is protected to prevent damage if connected to the wrong port.

Clamp Digital Multimeter

The clamp digital multimeter is used to measure the electricity flow. As the name suggests, this multimeter includes the feature namely clamp which measures the amps whenever the probes measure the volts. The adjustment of power utilization otherwise watts can be done through multiplying the reading of voltage with the amps. This multimeter also includes an additional feature that is different kinds of settings. The appropriate feature is used while measuring.

This kind of multimeter includes fixed tools for measuring the current flow. This device extremely changes from the fluke type because, in the fluke multimeter, it utilizes a clamp to measure the flow of current. So, this instrument is usually recommended for professionals only.

Autoranging Multimeter

The auto-ranging multimeter is a simple multimeter to utilize even though it is similarly the most costly of all kinds of digital multimeters. This multimeter includes a knob in the center and has less position. So it doesn’t switch automatically to measure. This instrument is applicable in simple projects. For beginners as well as electricians at home, this instrument is highly recommended. Generally, it measures a single component at a time.

Types of Multimeter Probes

A multimeter includes different test probes and the main function of these probes is to connect to the circuit under test. The most common types of probes are retractable hook clips, pointed probes & crocodile clips.

Generally, a multimeter includes two-color wires like black and red, known as leads or probes. One end of the probe is called a banana jack that is plugged into a multimeter, whereas the remaining end is known as the probe tip, used to test the circuit. The red probe is used for +ve whereas the black probe is used for –Ve.

These probes include a probe tip on one end whereas the other end includes banana plugs. Most of the multimeters include fuses to guard them against the extremely high current. When too much current supplies through the multimeter, this fuse will restrict the flow of current to prevent the damage. Some kinds of multimeters include fuses based on the measurement of low current or high current and they determine where you have to place the probes.

Working

Types of multimeter include two probes like red and black & two or three ports. From them, one of the ports is labeled.COM for common which is used for black probe whereas the remaining ports are labeled A used for amps and mA/µA (milliamps/microamps). The final port is labeled VΩ used for ohms & volts. Sometimes, this port is integrated into the 3rd one, which is next labeled mAVΩ.

If the multimeter includes four ports, then the red probe can be plugged into the VΩ port for measuring resistance as well as voltage. When the red probe is inserted into the mA port then the current can be calculated & plugged into the A port then the current can be measured in amps. For instance, the port used to test a diode using a multimeter is the VΩ port and this port can also be used to test a transistor.

Difference between Analog Multimeter and Digital Multimeter

The main difference between analog and digital multimeters include the following.

Analog Multimeter	Digital Multimeter
Analog Multimeter is used to gauge restricted electrical quantities like resistance, voltage & current.	Digital Multimeter is used to compute various electrical quantities like voltage, current, capacitance, resistance, values of diode and impedance, etc.
The size of the analog multimeter is larger	The size of the digital multimeter is smaller
This meter provides the reading on a scale next to the pointer.	This meter provides the reading in the form of numeric on an LCD.
These are calibrated manually.	These are calibrated automatically.
Its construction is simple	Its construction is complicated because of the involvement of components like electronics and logic.
Analog multimeters are less accurate because of the parallax errors & readings of the wrong pointer	Digital multimeters are very accurate
It doesn’t need ADC to show reading.	It needs ADC to exhibit the reading.
Input resistance is not stable	Input resistance is stable
The pointer of this multimeter tries to turn aside to the left in reverse polarity.	This multimeter shows a negative quantity once the polarity is reversed.
These are less cost	These are expensive
The o/p of this meter cannot be interfaced through exterior equipment.	The o/p of these meters can be interfaced through exterior equipment.
The frequency range is up to2kHZ.	The frequency range is high as compared to analog
Analog Multimeter measures the current with the help of a Galvanometer.	Digital Multimeter measures voltage with ADC
It has less electric noise	It has more electric noise
It allows simply one i/p signal for each operation.	It allows several input signals & consumers can select the required signal on the variable display.
The maximum AC frequency which can be calculated is lesser	The maximum AC frequency which can be calculated is high than its counter element

Advantages and Disadvantages of Digital Multimeters

The advantages of a digital multimeter include the following.

• It gives an automatic o/p display.
• The measurement results of the meter can record and store in memory and synchronizes through a PC
• It includes auto polarity functions
• The meter reading accuracy cannot depend on the charging of the battery
• It ensures accuracy
• Resistance toward mechanical damage.
• Multifunctionality
• Zero adjustments cannot be required
• Measurement accuracy is high
• Measuring ranges can be selected through manual or automatically

The disadvantages of digital multimeter include the following

• As compared to analog, it is expensive
• This multimeter does not work properly through measurement fluctuations. It can be tricky to discover one for your exact needs.

Advantages and Disadvantages of Analog Multimeter

The advantages of an analog multimeter include the following.

• Possibility of achieving measurements at below-30 ° С temperature
• Power utilization is not required from the fixed power supply while measuring current and voltage
• When high precision is not necessary, then quick operation through a large amount of measurement can be done.
• By using this instrument, all measurements can be done simply.
• The signal level can be observed

The disadvantages of analog multimeter include the following

• These meters are large
• These are expensive
• Voltage polarity cannot be recognized
• They are susceptible to vibration or shock.
• The movement of the pointer is slow and it cannot be utilized to measure voltages through frequencies above 50 HZ.
• Incorrect because of the earth’s magnetic field effect.
• An unexpected change in the signal can notice through an analog multimeter more quickly as compared with a digital multimeter.
• These are sensitive to vibration, mechanical damage.
• Input resistance is less, thus a high error while measuring less voltage

Types of Multimeter Applications

The applications of types of multimeter mainly involve various electrical and electronic projects for components testing and also used in different measurement applications in the multimeter.

Temperature and Environmental Applications

• Low-cost weather station
• DMM internal temperature

Voltage Measurements

• High and low-value DC measurement
• Peak to Peak and DC average measurement

Current Measurements

• DC measurement
• True RMS AC

Resistance Measurement

• Micro ohmmeter
• Measuring resistance with constant voltage
• Measuring resistance with constant current

Time and Frequency measurement

• Fast frequency
• Time measurement

Thus, this is all about an overview of different types of multimeter, their working, advantages, disadvantages, and applications. Most of the technicians know the value of multimeters, so they always carry them with their tool kit. These instruments help in detecting faults accurately. Generally, multimeters are used to measure resistance, inductance, frequency & conductance. Some of the meters are used for measuring temperature and duty cycle. But advanced meters are used with some features to measure decibels, microamps, RPM, etc. Multimeters are available with probes, leads & clams. Similarly, some of the meters come with warranties as well as additional batteries to help them for a long time.