- Digital Multimeter Definition: A digital multimeter is defined as a device that measures electrical parameters like voltage, current, and resistance, displaying the results digitally.
- Main Parts: The main parts of a digital multimeter include the display, selection switch, ports, and probes, each crucial for accurate measurements.
- Measuring Current: To measure current, connect the multimeter in series with the circuit and set the switch to the appropriate current range.
- Measuring Voltage: To measure voltage, connect the probes in parallel with the circuit component and set the switch to the voltage range.
- Checking Continuity: To perform a continuity check, set the multimeter to continuity mode and ensure the device beeps when the probes touch two points, indicating a low resistance path.
A digital multimeter is defined as a device used to measure electrical parameters such as voltage, current, and resistance. The term “digital” means it has a digital display, and “multimeter” means it can measure multiple parameters. A typical digital multimeter includes a selection switch, display, ports, and probes.
Insert the probes into the appropriate ports and connect them across the parameter to be measured. Ensure the selection switch is set to the correct position for the measurement. The multimeter will then display the value of the parameter.
Digital multimeters are generally used to measure three main parameters: current, voltage and resistance. They can also perform special functions like diode checks, capacitance measurement, Transistor hFE (DC current gain), frequency measurement, and continuity checks. This article covers the most common uses of a multimeter: measuring current, voltage, resistance, and performing diode and continuity checks.
Current Measurement by Using a Digital Multimeter
To measure current with a digital multimeter, it mimics an ammeter. Insert the red probe into the mA socket for low current or the 20A socket for high current. Connect the meter in series with the circuit. Set the switch to the expected current range. When the power is on, the meter will display the current flowing through the circuit.
Voltage Measurement by Using a Digital Multimeter
To measure voltage with a digital multimeter, it acts like a voltmeter. Insert the red probe into the ‘V’ socket and the black probe into the ‘COM’ socket. Select the expected voltage range and choose either AC or DC. Connect the leads in parallel with the component or point where the voltage is measured. The meter will display the voltage value.
Resistance Measurement by Using a Digital Multimeter
In this case, we configure the multimeter to act like an ohmmeter. Here the red and the black probes of the multimeter are inserted into the sockets marked as ‘V’ and ‘COM’, respectively while the selection switch is set to an expected range in ohmmeter region (Figure 1). Now, the leads need to be connected across the component whose resistance is to be known. On doing so, we get a reading in the display part of the multimeter which reads the value of the resistance.
Diode Check by Using a Digital Multimeter
For this case, insert the probes into the sockets as that in the case of voltage measurement and set the selection switch to point towards diode check position shown in Figure 1. Now when the red lead of the multimeter is connected to positive terminal of the diode while its negative lead is connected to the negative terminal of the diode, then we have to get a low reading on the multimeter. On the other hand, if we connect the red lead to the negative terminal of the diode and the black to the positive terminal, then we have to get a high value. If the readings obtained are as per our expectation, then we say that the diode is working properly; else no. More information regarding this can be found in the article “Diode testing”.
Continuity Check by Using a Digital Multimeter
Continuity check is used to know whether there exists any low resistance path via two points i.e. to check whether the points are short or not. To accomplish this task, the probes are inserted into the sockets as that in the case of voltage measurement and selector switch is made to point towards continuity check position (Figure 1). Then, the points to be tested are touched with the leads of the probes. Now, if the multimeter beeps out, then it means that the points are shorted or else the resistance between them can be read out from the display.
