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A Digital Multimeter (DMM) is an electronic measuring instrument used to test and troubleshoot electrical circuits. It combines several measurement functions in a single device, typically including the ability to measure voltage, current, and resistance. Advanced models may also measure other parameters like capacitance, frequency, temperature, and continuity.
This video provides a comprehensive guide to using a multimeter, covering essential features like voltage, resistance, continuity, and capacitance. It explains how to use each feature, demonstrates practical applications, and discusses important safety precautions. The video also helps viewers choose the right multimeter based on their needs and budget.
Review the video then review the layout and Icons as well as their meanings in the diagram below. Check out the Electronics Hub for additional information. https://www.electronicshub.org/multimeter-symbols/
The DMM can be used to measure Voltage and current, but the connections required are different for the two measurements. In the case of measuring voltage, the DMM is connected in parallel with the load. When reading Current, the meter must be connected in series with the circuit.
IMPORTANT THAT IF YOU TRY TO MEASURE VOLTAGE WITH THE METER SETUP FOR CURRENT, YOU WILL SHORT OUT THE DEVICE AND COULD CAUSE INJURY, DESTROY YOUR METER OR DESTROY THE CIRCUIT YOU WERE TRYING TO MEASURE.
Measuring Voltage and Resistance
Measuring Voltage and Resistance
How to Measure Voltage
How to Measure Voltage
Power off the circuity/wiring under test if there is a danger of shorting out closely spaced adjacent wires, terminals or other points which have differing voltages.
Plug the black ground probe lead into the COM socket on the meter (see photo below).
Plug the red positive probe lead into the socket marked V (usually also marked with the Greek letter "omega" Ω and possibly a diode symbol).
If the meter has has a manual range selection dial, turn this to select AC or DC volts and pick a range to give the required accuracy. So for instance measuring 12 volts on the 20 volt range will give more decimal places than on the 200 volt range.
If the meter is autoranging, turn the dial to the 'V' setting with the symbol for AC or DC (see "What Do the Symbols on the Range Dial Mean?" below).A multimeter must be connected in parallel in a circuit (see diagram below) in order to measure voltage. So this means the two test probes should be connected in parallel with the voltage source, load or any other two points across which voltage needs to be measured.
Touch the black probe against the first point of the circuitry/wiring.
Power up the equipment.
Touch the other red probe against the second point of test. Ensure you don't bridge the gap between the point being tested and adjacent wiring, terminals or tracks on a PCB.
Take the reading on the LCD display.
How to Measure Current
How to Measure Current
To measure current with a digital multimeter (DMM), you must connect the multimeter in series with the circuit so that the current flows through the meter.
Steps to Measure Current
Steps to Measure Current
Turn Off Power:
Ensure the circuit is powered off before connecting the multimeter to avoid damage or incorrect readings.
Set the Multimeter:
Turn the dial to the appropriate current measurement mode:
DC Current (A or mA) for direct current circuits.
AC Current (~A) for alternating current circuits.
If unsure of the current range, start with the highest current setting to prevent overloading.
Insert the Probes:
Insert the black probe into the COM port.
Insert the red probe into the correct port for current measurement:
Use the A port for high currents (usually above 200 mA).
Use the mA/µA port for low currents.
Break the Circuit:
Open the circuit at the point where you want to measure current. This might involve disconnecting a wire or removing a component.
Connect the Multimeter in Series:
Attach the red probe to the power source or upstream side of the circuit.
Attach the black probe to the downstream side, completing the circuit through the multimeter.
Turn On Power:
Power the circuit and observe the current reading on the multimeter's display.
Interpret the Reading:
Note the value and units (e.g., milliamps or amps). If the reading is negative, reverse the probe connections.
Turn Off and Disconnect:
Turn off the power before removing the multimeter and reconnecting the circuit.
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