# How to use a digital multimeter

A multimeter, also called a volt-ohm meter or VOM (in Russia we call it a tester), is a device that measures resistance, voltage, and current in electronic circuits. Some of them also test diodes and conductivity. Multimeters are small, lightweight and battery operated, and can test a wide variety of electronic components in many situations, making them indispensable tools for anyone who needs to test and repair electronic circuits.

## Steps

### Method 1 of 5: Measuring Resistance

#### Step 1. Connect a multimeter to the circuit

Insert the black test lead into the common terminal and the red test lead into the connector marked for volt and ohm measurements. The terminal can also be marked for diode testing.

#### Step 2. Turn the knob to set the multimeter to measure resistance

This can be represented by the Greek letter omega, which stands for ohm, a unit of measure for resistance.

#### Step 4. Remove the resistor you want to measure

If you leave a resistor in the circuit, you may not get an accurate reading.

#### Step 6. Read the display, noting the units

10 can indicate 10 ohm, 10 kilo ohm, or 10 megohm.

### Method 2 of 5: Measuring Voltage

#### Step 1. Connect a multimeter to the circuit

Insert the black test lead into the common terminal and the red test lead into the connector marked for volt and ohm measurements.

#### Step 2. Set the multimeter to the voltage you are measuring

You can measure DC voltage, DC millivolts, or AC volts. If your multimeter has an AutoRange function, this is not necessary.

#### Step 3. Measure AC voltage by connecting to components

It is not necessary to observe the polarity.

#### Step 4. Observe polarity when measuring DC voltage or millivolts

Connect the black test lead to the negative side of the component and the red test lead to the positive side.

### Method 3 of 5: Measuring Current

#### Step 1. Select either the terminal labeled for 10 amps or labeled for 300 milliamps

If you are unsure of the amperage, start at the terminal with 10 amps until you are sure the current is less than 300 mA.

#### Step 2. Set up a multimeter to measure current

This can be indicated by the letter A.

#### Step 4. Break the chain

To measure current, you must place a multimeter in series with the circuit. (Black test lead on negative pole, red test lead on positive pole) Place the test leads on either side of the break, observing the polarity.

#### Step 5. Turn on the power

Current will flow through the circuit, to the red probe and through the multimeter, from the black probe and into the circuit.

#### Step 6. Read the reading, remembering whether you are measuring amps or milliamps

You can optionally use the touch hold feature.

### Method 4 of 5: Testing Diodes

#### Step 2. Use the knob to select the diode test function

This can be represented by a symbol representing a diode, an arrow pointing to a vertical line.

#### Step 4. Check forward bias

Place the red test lead on the positive side of the diode and the black test lead on the negative side. If you get a measurement less than 1 but greater than 0, the forward bias is good.

#### Step 5. Swap the test leads to check the reverse bias

If the display shows "OL (overload)", it means that the reverse bias is good.

### Method 5 of 5: Measuring Conductivity

#### Step 4. Connect the wires on either side of the section of circuit you are testing

It is not necessary to observe the polarity. A reading of less than 210 ohms indicates good electrical conductivity.