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# How to Use Multimeters

Modified 2019-09-05 by nkumar15-brown-university

During this step you will learn about how to use multimeters to do a continuity check and a voltage check.

A multimeter or a multitester, also known as a VOM (volt-ohm-milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance. This is a general tutorial for multimeters.
NOTE: Please turn off the multimeter by setting the dial to OFF after you finish your check.

## Continuity Check

Modified 2019-09-20 by nkumar15-brown-university

In electronics, a continuity check is a test of the resistance between any two points of a circuit (that it is in fact a complete circuit). If there is zero resistance between two points, then there is a short between the points. Shorts are potentially dangereous because they may cause far too much current to flow throughout the circuit - thus resulting in the circuit frying due to heat generated by friction.

Performing a continuity check is a safe way to debug if a circuit has an undesired short because the check does not require a power source to be connected to the circuit.

1. Select the Continuity Function

• Turn the multimeter dial to the continuity test position. Then press the “FUNC.” button to switch to the continuity test mode (indicated by an icon that looks like a sound wave).

Continuity test dial position Continuity test mode
• Test the continuity test mode by touching and holding the multimeter leads together. A continuous beep will be audible for as long as the leads are held together.

Leads held together (a continuous beep is audible)
2. Perform the Continuity Check

• Place each lead at a point of the circuit or component you want to test.

• If the path between the two points is continuous (i.e. is a short), then the screen will display a value of zero (or near zero) and the multimeter will emit a continuous beep for as long as the leads are held in place. Note: if you hear a short beep followed by silence while the leads are held in place, then you can safely ignore the short beep.

General Continuity Check Strategy:

• Check every two positive (+) terminals to make sure every pair of these terminals is continuous.

• Check every two negative (-) terminals to make sure every pair of these terminals is continuous.

• Check every positive terminal (+) to make sure it is not continuous with any negative terminal (-).

## DC Voltage Check

Modified 2019-09-20 by nkumar15-brown-university

1. Selecting the DC Voltage Mode
2. Switch on your multimeter, and set the dial to DC voltage mode (indicated by a V with a straight line, or the symbol ⎓).

3. Performing the Voltage Check

4. Place the positive (i.e. red) lead on a positive (+) terminal, and the negative (i.e. black) lead on the negative (-) terminal.
5. See the screen for a voltage measurement.
6. NOTE: Reversing the leads (i.e. red on - and black on +) won’t do any harm; it will simply give a negative reading of the same magnitude.

## AC Voltage Check

Modified 2019-09-04 by andrewkpeterson

1. Selecting the AC Voltage Mode
2. Switch on your multimeter, and set the dial to AC voltage mode (indicated by a V with a wavy line, or the symbol ṽ).
3. NOTE: AC voltage does not have polarity.
4. NOTE: Do not let your fingers touch the lead tips. Do not allow the tips to contact one another.

5. Performing the Voltage Check

6. Place the positive(red) lead on the positive terminal, and the negative(black) lead on the negative terminal.
7. We can get a reading from the screen now.
8. NOTE: Reversing the leads won’t do any harm; it just gives us a negative reading.

This contains more detailed information about AC voltage test.