What is a multimeter?

A Multimeter can be described as a tool for electrical measurement, it is a combination of different kinds of electrical meters. We can use this device to do the measurement of voltage, current, resistance, etc. So we use a multimeter to measure AC/DC voltage, AC/DC current, and resistance. The multimeter has got its name because it does the functions of Ammeter, Voltmeter, and Ohmmeter. A multimeter can also be used to do the continuity test, we can check the continuity between two points in an electrical circuit by using a Multimeter.

What are the types of multimeters?

Mostly there are two types of multimeter they are Analog and Digital multimeter

Analog Multimeter

Analog multimeter consists of analog scale this multimeter is less accurate when compared to the digital one because there could be many errors while reading an analog multimeter. Most of the errors are human errors while reading the scale.

Digital Multimeter

A digital multimeter is the latest one and uses a digital scale and the display is digital so there will be less error and thus accurate reading is possible.

What are the advantages of Digital Multimeter over the Analog Multimeter?

A digital multimeter is capable to measure the additional electrical quantities, we can use a digital multimeter to calculate the current, voltage, resistance, capacitance, inductance, and impedance. Another important advantage of the digital multimeter is that it can be used to test different electronic components. We can check a resistor, capacitor, diode, transistor, relay, etc.

What are the major functions of a multimeter?

• The amount of voltage in a circuit can be determined
• We can determine the amount of current that passes through a circuit
• Measurement of resistance
• We can determine the wiring errors
• Measurement of capacitance
• We can test different electronic components
• Temperature measurements
• Frequency measurement

How to use a multimeter?

In the above image, we can see a selection knob that can be used to set the multimeter for different measurements. We can see different symbols in a multimeter such as the resistance symbol, capacitance symbol, etc. So place the knob in the section of the symbol in which you need to do the measurement. In order to do the measurement, you need to move the knob to the unit which you need to measure and also the exact range that you need to take the measurements.

We can see two probes in the multimeter and this will be connected to the two ports of the multimeter. The probes or the test leads can be used to connect the measuring device to the measuring object. COM stands for common and it will be connected to the ground of a circuit. There is a black and red probe but there is no difference between them except for the color. The 10A jack is the special port that is used to do the measurement of a large current. VΩmA is the port to which the red probe is mostly connected. This port can be used to do the measurement of current, voltage, resistance, etc.

How to use a multimeter step by step?

To use a multimeter effectively for various measurements, you need to follow these steps based on the type of measurement:

How do you measure with a multimeter?

Measuring Voltage (AC/DC):

• Set the knob to the appropriate voltage type (AC or DC) and range.
• Connect the probes: Insert the black probe into the “COM” port and the red probe into the “VΩmA” port.
• Connect the probes to the circuit: Place the probes across the voltage source or the component you’re measuring. The multimeter should be in parallel to the object being measured.
• Read the display: If you’re measuring AC voltage, it will convert to equivalent DC voltage before being displayed.

Measuring Resistance:

• Set the knob to the resistance range (symbolized by Ω).
• Ensure the circuit is powered off before measurement.
• Connect the black probe to “COM” and the red probe to the “Ω” port.
• Touch the probes to the component or circuit portion you’re measuring the resistance in.
• Read the resistance value on the display.

Measuring Current (AC/DC):

• Set the knob to the correct current range.
• Connect the black probe to the “COM” port and the red probe to the current port (10A for large current or VΩmA for small current).
• Interrupt the circuit and connect the multimeter in series with the circuit where current is flowing.
• Reconnect the power source and turn it on to complete the measurement.
• Read the value on the display.

Testing Continuity:

• Set the knob to continuity mode (represented by a diode symbol or sound wave).
• Connect the black probe to “COM” and the red probe to the VΩmA port.
• Place the probes on both ends of the wire or circuit to test continuity.
• If the circuit is complete, the multimeter will beep, indicating continuity.

Additional Tips for Using Multimeter

• Ensure polarity is correct when measuring voltage and current.
• Autoranging feature: Some multimeters automatically select the correct measurement range, simplifying usage.
• Temperature and frequency measurement: Some advanced multimeters can measure temperature and frequency, which requires switching the knob to the appropriate mode.

By following these procedures, you can effectively use a multimeter for a variety of electrical measurements.

How does a multimeter work?

As we can see in this diagram in a digital multimeter the input signal which could be AC/DC, voltage, resistance, or any other parameter would be converted to DC to the range of ADC. Then this signal will be converted to its equivalent digital numbers by ADC and it will be displayed in the display unit. Mostly all the multimeters would operate on this manner.

What are the different symbols in a Multimeter?

Multimeter Symbols:

• V: Voltage (AC/DC)
• Ω: Resistance
• A: Current
• Diode Symbol: Continuity test
• Capacitance Symbol: For capacitance measurement

How to measure voltage by using a multimeter?

AC & DC voltage

As we discussed earlier, we can see two probes in the multimeter we need to connect the unknown AC/DC voltage across the input probe. Multimeter should be connected parallel to the voltage source or to the object which is to be measured. In order to do the AC/DC voltage measurement, select the AC voltage range by the knob. In case of measuring the DC voltage then select that range by using the knob. The voltage would attenuate if it is more than the selected range, so we need to select a range that could be greater than your expected reading. During the measurement of the AC voltage, it will be converted to the equivalent DC voltage then it will be transmitted to the AD converter to show the voltage in the digital display. The same process would be done for the DC voltage measurement except there won’t be any conversion to DC. Also, make sure the polarity is correct while doing the measurement.

How to measure resistance by using a multimeter?

In order to measure the resistance, set the multimeter in the resistance range. Before measuring the resistance in a circuit, you must disconnect the circuit from the power source. After that connect the black probe to the COM input jack and the red probe must be connected to the Ω input jack. Then connect the tip of the probe across the component or portion of the circuit in which you need to measure the resistance.

How to measure current by using a multimeter?

In order to measure the current in a circuit, we need to connect the multimeter to the circuit or interrupt the circuit. We need to turn the knob to the current range before taking the measurements. Due to this connection, the electrons would flow through the meter, the meter must be connected in series to a circuit if you are measuring the current in a circuit. After connecting the multimeter to the circuit reconnect the power source and turn it on. Also, make sure the polarity is proper while doing the measurement.

How to test continuity by using a multimeter?

A continuity test is done to determine the completeness of the circuit like there is a proper flow of electricity. So if there are no broken wires or connectors then there will be continuity in the circuit. In order to test the continuity, you need to place the probes in a circuit and if there is continuity between the two probes then you can hear a beep sound. So we can determine the bad connections or breaks in an electrical circuit. 

What are the various multimeter brands available in the market?

• Fluke
• Brymen
• Extech
• Amprobe
• Klein tools
• Innova multimeters
• Mastech
• Tekpower
• Etekcity

Different categories in multimeters

Fluke multimeter

We can use this multimeter to do the measurement of voltage, electrical resistance, pressure, humidity, frequency, temperature, etc. Mostly this type of multimeter is used for calibration purpose, it can be used to calibrate the volt, current, and also other electrical units. These multimeters are immune to transient voltage

Clamp multimeter

These multimeters are used to determine the flow of electricity, so in this multimeter, a clamp is used to measure the flow. This type of multimeter can be used to measure the power flow, voltage, consumption of power, wattage, and amps. In order to do the measurement, the clamp is attached to the area where the measurement should be done. The major difference between a clamp meter and a normal multimeter is that we don’t need to connect this meter to the circuit instead you can place the clamp in the place where the measurement should be done. So there is no direct contact in this measurement. Safe measurement is possible by the clamp meter.

Autoranging multimeter

This is like a normal multimeter but it has an auto-ranging feature, this meter would automatically choose the range to do the measurement. We can use this multimeter to measure the resistance, capacitance, voltage, current, and many other electrical parameters. So it would automatically choose the voltage, current, or resistance range to do the measurement while connecting with the circuit or the device

What are the different measurements using a multimeter?

A multimeter can measure several electrical parameters, including AC/DC voltage, AC/DC current, resistance, continuity, capacitance, temperature, and frequency. Some advanced multimeters can also measure diodes and transistors.

How can we measure different parameters with a multimeter?

To measure different parameters:

• Voltage: Set the knob to AC or DC voltage and connect the probes across the circuit in parallel.
• Current: Switch to the current range and connect the multimeter in series with the circuit.
• Resistance: Set to the resistance range and place the probes across the component with the power off.
• Continuity: Use the continuity mode, connect the probes, and listen for the beep indicating circuit completeness.

Features comparison between various multimeters