Basics of Digital multimeter | How to use digital multimeter?


It is called a multimeter because it combines the functions of a voltmeter, ammeter, and ohmmeter. Multimeters may also have other functions, such as diode and continuity tests.

Electronic multimeters are sometimes also called AVO-meters, basically, this tool is a combination of measuring instruments in the same direction, voltage, resistance, alternating voltage.

Digital multimeter (DMM) give more accurate reading then analogue multimeter. It is also easy to read the measured value. Many DMMs can also record measurements over a period of time. This data logging capability can be useful in several applications.

The red wire of the meter is connected to the voltage/resistance or amperage port and the positive connection is considered. The black cable of the meter is connected to the common / ground port and the negative connection is considered.

Common DMM Symbols

Measuring Resistance and Continuity

  • Connect the probes across the resistor or equipments and put the knob at the expected value range in ohm function.

  • Continuity test is used to verify if a circuit is complete with no open.

  • Disconnect power source before testing

  • Remove component or part from system before testing.

  • Measure using lowest value, if OL move to next level

  • The multimeter will gives a beep audio if the circuit is complete.

  • If there is no audible alarm, there should be a resistance reading of 0.1 ohm to 1 ohm.

Measuring Voltage

  • Voltage has two section in multimeter, Alternating Current (AC) is house voltage (110vac), Direct Current (DC) is battery voltage (12vdc).

  • On switched meters use one value higher than your expected value

  • Be careful about, not to touch the tips to each other while connected to anything else.

  • Connect the multimeter parallel to the circuit where the voltage is to be measured.

  • The multimeter provides a parallel path, so it must be of high resistance to allow the lowest possible current to flow

Measuring current:

  • Current is measured in amps or amperes

  • Put the multimeter to highest current setting if you are working with the current source

  • Place the multimeter series with the circuit to know the current in the circuit