A multimeter is also called AVO Meter. Actually, it is a combination of three meters i.e volt meter, current meter, and ohm meter. Moreover, it can also be used to check both AC & DC voltage.

Define Multimeter

The Best Multimeter is an electrical tool that can be used to measure resistance, voltage, and current of a circuit. However, some multi-meters are used to measure frequency. Mainly, there are two types of multimeters. One is analog and the other is digital.

Controls and terminals of a Multimeter are

  1. Switch for Function: Select the function (voltmeter, ammeter,ohm-meter) and the range is used for the measurement
  2. COM Input Terminal
  3. Volt Input Terminal
  4. 200 mA Input Terminal
  5. 10A Input terminal

Resistance Measurement

A multimeter can be used to check the resistance of any electronic component. Turn on the meter and select the resistance to measure resistance measurement. Now insert two wires in the jacks labeled V-resistance and COM. The multimeter now can be used to measure the resistance of a component connected between these two wires.

Voltage Measurement

First of all, remove all the connected wires. Turn ON the meter and select V – for DC voltage or V – mode for AC voltage. Insert a red wire in the jack labeled VΩ and a black wire in the jack labeled COM. When making voltage measurements, make certain the voltmeter is connected in parallel with the circuit components across which voltage is measured.

Current Measurement 

If there are wires already connected then 1st of all, we remove all the connected wires. Likewise, Turn ON the meter but here select A for ammeter mode. Insert a red wire in the jack labeled “A” while the black wire in the jack is labeled COM. For current measurements, make certain the ammeter is connected in the series with the circuit components through which the current is measured.

MULTIMETER OPERATION

You should follow these safety guidelines.

 • Never operate a multimeter unless the battery cover is in place and fully closed.

 • Never connect a source of voltage with the function switch in the OHM () position or the DIODE position.

 • Don’t replace the battery or fuse unless the test leads have been disconnected and the power is OFF.

 • When making current measurements, make certain one of the multimeters is connected in series with the load. Never connect the meter in parallel to measure current. To do so can result in blowing the overload protection fuse or damaging the device being tested.

Resistance Measurements

Resistance Measurement Procedure

 Resistances into the megohm range can be measured with a multimeter. The multimeter can also be used for measuring the continuity of practically every electrical device made. The procedure is as follows:

1. Remove all sources of power from the device or resistor being tested.

 2. Insert the test leads into the meter.

 3. Select the range and connect the test leads across the resistor under measurement

CAUTION: Never apply a voltage or current to the test leads when the function/range switch is in position. A good habit is to always check the function/range switch position before making measurements.

 Note: After resistance measurements are made, ALWAYS turn the function/range switch to the OFF position. This will help prevent the meter from being damaged and increase the life of the battery.

DC Voltage Measurement

DC Voltage Measurement Procedure

 1. Insert the test leads into the meter.

 2. Select a higher VDC range than you anticipate measuring. For example, to measure 700 VDC, select the 1000 VDC range. If the magnitude of voltage isn’t known, select the highest range.

WARNING: Use extreme caution to avoid contact with the circuit when measuring voltage.

3. Connect the test leads across the source or device being measured Voltage value will appear on the digital display along with the voltage polarity.

 4. Reduce the setting until a usable reading is obtained.

 5. Disconnect the test leads.

DC Voltage Measurement Setup

AC Voltage Measurement

AC Voltage Measurement Procedure

1. Insert the test leads into the meter.

 2. Select a higher VAC range than you anticipate measuring. For example, to measure 120 VAC, select the 200 VAC range. If the magnitude isn’t known, select the highest range.

WARNING: Use extreme caution to avoid contact with the circuit when measuring voltage.

3. Connect the test leads across the source or device being measured. The voltage value will appear on the digital display.

 4. Reduce the range until a satisfactory reading is obtained.

 5. Disconnect the test leads.

DC Current Measurement

DC Current Measurement Procedure

1. Insert the test leads into the meter.

 2. Turn OFF the power to the device being measured.

 3. An ammeter must be placed in series with the branch circuit through which the current is to be measured. To do this, open the branch at some convenient point and connect one test lead to each side of the break

CAUTION: Always place an ammeter in series with the circuit. Never place it across or in parallel with the circuit. Doing so can cause a short circuit to the source and can damage the multimeter.

 4. Select a higher DCA range than you anticipate measuring. If the magnitude of the current isn’t known, select the highest range and reduce the setting until a satisfactory reading is obtained.

 5. Read the current value and polarity on the display.

 6. De-energize the circuit, disconnect the test leads, and restore the circuit to its pretest condition.