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Basic Functions and Use of A Digital Multimeter

I wanted to share a quick post regarding using a digital multimeter. This is intended to be a brief introduction into how multimeters work and their basic functions. Every electrician apprentice should know the basic functions and how to use a digital multimeter.

This post is designed to give you a basic understanding of what a digital multimeter is and how to use one. For a more indepth learning experience I recommend you check out this article from allaboutcircuits.com.

What Is A Digital Multimeter?

A digital multimeter or DMM is one of the most useful items of test equipment to diagnose electrical or electronic problems. It’s a measuring device that takes analog information and converts it into a digital signal which reads out on the display.

digital multimeter reading analog versus digital signal
Credit: Mixrev.com

 

You can use a digital multimeter for measuring the following:

  • AC voltage
  • DC voltage
  • Current
  • Resistance
  • Temperature
  • Frequency
  • Capacitance

Of course this all depends on the type of digital multimeter you have. At a minimum you should be able to measure voltage, resistance, and current with any digital multimeter.

 

How To Use A Digital Multimeter To Test Voltage

Testing a circuit (or source of power) for voltage is the most common use of a digital multimeter. Here’s how you would test different circuits for voltage.

DC or Direct Current Circuits

  1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
  2. Turn on your multimeter and place the selector switch to the V with the solid and dashed line (VDC).
  3. Now connect the test leads to the circuit: black to the negative potential point (which is the circuit ground) and red to positive potential point.
    a digital multimeter measuring dc circuit
    Credit: www.electronicshub.org

You should now see a reading on the display. The display is now showing the voltage of the source (battery) or circuit. If you see a – symbol in front of the reading then switch your leads (this means the polarity is backwards). If you don’t see a reading then check to make sure you’ve selected the correct setting and the leads and the leads are connected correctly. Still no reading? The source is either dead or the circuit is off.

AC or Alternating Current Circuits

  1. Install your test leads into the proper terminals on the meter. Black lead into the common or COM port and the red lead into the port labeled ∨Ω.
  2. Turn on your multimeter and place the selector switch to the  with the wave.
  3. Since it’s AC, lead placement doesn’t matter but you still need to know what readings to expect on conductors or receptacles.

 

I found a  great video on YouTube that gives you a basic understanding of how to use a digitial multimeter. For those of you who like to read, keep doing so.

 

 

I also found some great resources for you to check out if you need some more input. Fluke put together a digital multimeter fundamentals library that breaks down the DMM functions and how to use a DMM for certain applications. Check it out here.

Also check these out:

All About Circuits

Spark Fun

 

 

 

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About Alex M

Alex M
Hard Work Puts You Where Good Luck Can Find You

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