How to Use a Digital Multimeter

Even though a digital multimeter is an indispensable tool that you must have in your toolbox, there is a learning curve involved before using one. Just like a stethoscope is to a doctor, a multimeter is essential to an electrical engineer. In fact, it might be the first tool you will be introduced to if you are looking to explore anything to do with electronics.

First things first, we need to understand what a multimeter is and what it measures;

A multimeter, also known as a volt-ohm meter (VOM), is a tool that is used to measure voltage, resistance, and continuity. Although these are the basic measurements, it is not only limited to them; it can also measure frequency, capacity as well as gain of transistors. In short, we can safely say that a multimeter is an amalgamation of a voltmeter, ohmmeter, and ammeter.

There are two types of multimeters; analog and digital. However, in this article, we will only focus on the digital multimeter. This is because the digital multimeter, also known as the DMM, is the most commonly used; it can display and record accurate data.

Is there a difference between an analog and a digital multimeter?

Yes definitely!

While there are many differences between the two, the main distinguishing factor is by the parameter of representation. While an analog multimeter displays the quantity of measurement by a pointer on the scale, a digital multimeter displays the value in a digital format, i.e., using digits.

A digital multimeter (DMM) is surprisingly a very useful instrument to own. It can be used to test, diagnose, and troubleshoot circuitry, components, and other electrical devices.

Before we go any further, see the below entities of a basic digital multimeter.

  • Current (A)
  • Voltage (DCA and ACV or ~)
  • Resistance (Ω)
  • Capacitance (F)
  • Diode test
  • Continuity

Other than that, you will also find these parts in a DMM.

  1. Probes– A digital multimeter has two probes; red (positive)and black (negative). Each probe features a metal strip used to connect your meter to the electric measuring devices.
  2. Dial– It is used to select the measuring entity. The dial may be different depending on the type of DMM.
  3. Display– The display indicates the digital reading of the entity.
  4. Slots– Slots are used to connect two probes. You may find the slot configuration on the red probe different for different digital multimeters.

Also, note that;

  • COM slot is where the black probe is connected.
  • VΩmA slot is where the red probe connects. It is mainly used when measuring resistance, voltage, capacitance, continuity, diodes, or current (when less than 200mA). 
  • 10A slot is used to measure currents that are higher than 200mA. Even though measuring other entities using this slot will not harm your multimeter, it will give inaccurate readings.

So, if you are looking to use a digital multimeter and have no idea how to go about it, sit back and read through!

  1. How to measure voltage using a digital multimeter

Generally, there are two types of voltages; AC (Alternating Current) and DC (Direct Current). A DMM can measure these two.  AC voltage is used to test things mainly found in the house, such as sockets, washing machines, and microwaves. DC voltage, on the other hand, is used to measure batteries and other electric components. Since DC voltage is the most used measurement parameter, it is quite common.

For both DC and AC parameters, use the following steps;

  • To begin, use the voltage setting for both DC and AC settings.
  • Plug in the test leads into the COM slot and the V terminals. The black probe should be plugged into the slot labeled ”COM (common)” while the red probe should be plugged into the slot labeled V (voltage).  Both AC and DC voltages are measured in this manner.
  • If you want to measure the AC voltage, proceed to move the dial to V~. This setting is used to measure voltage in a socket, washing machine, TV, and other electronics in the house.
  • Move the dial V⎓ if you want to measure DC voltage. This range is mostly used to measure the batteries.

In case you accidentally measure the AC voltage on a DC setting and vice versa, the multimeter will not be affected. However, the voltage should always be set at the highest.

  • Always set the dial to a higher number than the voltage you are measuring. And remember, if you measure a battery, set the dial to the DC, and if you measure electronics, set the dial to the AC.

Please note; if you measure a wall socket and the AC section is 110V, set the dial to 200V.

  • If you are measuring a DC voltage, position the wire probes on the negative (black) and positive (red) circuit. Hold the wire probes to each end and make sure that they touch the metal section on the corresponding end.
  • Place the probes in the correct slot in the socket when measuring the AC voltage. The black probe is inserted into the bigger slot while the red probe goes into the smaller slot next to it.

Always do it correctly to avoid getting shocked. Always keep your fingers from the tips of the probe and never let the probes touch each other.

  • Finally, look at the display screen to see the reading.
  • How to test for resistance using a digital multimeter

Resistors are the most common components in electronics. Therefore, there is a broad spectrum of resistors based on the resistance value and the power rating. The value of the resistors is read using the color codes. To measure the resistors;

  • Always disconnect whatever you are testing before from the power source.
  • Make sure that the black probe is on COM while the red is on terminal Ω (V sign).
  • Detect the area represented by the resistance sign and turn the dial to the located section.
  • Continue the process by setting the dial to a higher number above what it’s expected. Keep twisting until you get a precise reading.
  • Put the probe twist on to each end of the resistor.
  • How to test continuity using a digital multimeter

A digital multimeter plays a big role in testing the continuity of a circuit. This is necessary in case there is a broken wire.

To measure the continuity of between two points in a cord;

  • Make sure the device you are testing is not connected to the power source.
  • Put the black probe in COM and the red probe in Ω (V) terminal.
  • Set the dial to the location that has a continuous sound wave symbol.
  • Place the probes to their corresponding end. For it to work correctly, make sure that the black and red probes are touching the wire simultaneously.
  • If your wire is working, you will hear a beeping signal, and if not, you will know that there is a short.
  • How to check components using a Diode/LED mode

Place the black probe on COM and the red probe on the V slot. Turn the dial on the Diode symbol. After, position the black probe on the cathode and the red one on the anode. It should make an LED glow. Therefore, you will know that it is working.

Conclusion

It’s worth noting that a digital multimeter is an essential instrument. If you are an electrical enthusiast, you should own one.

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