Digital multimeter

Introduction

A Digital multimeter is test equipment that offers several electronic measurement tasks in one tool. It is also known as the voltmeter or ohmmeter or volt-ohm meter. The standard and basic measurements performed by a multimeter are the measurements of amps, volts, and ohms. Apart from that, these digital multimeters perform many additional measurements by using digital and logic technology. These may include temperature, frequency, continuity, capacitance, etc.

The digital multimeter is a versatile instrument that contains three different meters in one.

1. A voltmeter measures the voltage across a component (in volts).
2. An ohmmeter measures the resistances of a component (in ohms).
3. An ammeter measures the amount of current through a component (in amperes, or amps)

Parts of digital multimeter 

• A multimeter is a simple but useful device that has only three parts
• Display screen
• Selection knob
• Ports.

  Display screen

• Display screen-It has an illuminated display screen for better visualization.
• It has five digits display screen; one represents significant value and the other four are for number representation.

Selection knob

• As we know a single multimeter performs so many tasks like reading voltage, resistance, and current.
• The selection knob allows the user to select the different jobs.

  Port

• There are two ports on the front of the unit. One is the mAVΩ port which allows the measurement of all the three units: current up to 200 mA, voltage, and resistance. The red probe is plugged into this port.
• · The other is COM port which means common and it normally connected to -ev of a circuit and a black probe is plugged into it. There is one particular port is 10A, which is used to measures a large current in the circuit.

Features of digital multimeter 

● Auto-Rang

● A Back-Lit LCD

● Auto-Off

● Decent Probes

● Auto Polarity

Block diagram

• Voltage Measurement by using a digital multimeter 

●  When set to measure the voltage, the multimeter acts like a voltmeter.

● To start with, one has to insert the red and the black probes of the multimeter to the sockets marked as ‘V’ and ‘COM’, respectively.

● Then we have to select the expected range in which our voltage would be. Simultaneously, even AC or DC should also be selected in the voltmeter section of the figure.            

  Resistance Measurement By Using a Digital Multimeter

● Set the dial to a value greater than the resistor value being measured.

● For a 5000 ohm resistor, set the dial to 20k

● The 1 in the display means the resistance is higher than the current dial setting

● For a 300ohm resistor, set the dial to 2000

                                                             Diode Check By Using a Digital Multimeter 

Digital Multimeter Layout

● The top portion of the meter contains the digital readout area which displays the measurement value.

● Below the digital readout is a black dial, called the FUNCTION switch.

● The FUNCTION switch dial is turned to select the meter’s function that is voltmeter, ammeter, or ohmmeter.

Function Switch Dial  

● There are eight different functions to choose from on the function switch.

● The first is OFF. The meter should always be returned to this position when not in use.

● The V markings are for measuring DC and AC voltage.

● The Ω marking is for measuring resistance.

● The A marking is for measuring current.

Function Switch Measuring Resistance and Current

● The Ω is used to measure electrical resistance in ohms.

● The A setting is used to measure DC current in amps.