Working function of multimeter

1. MULTIMETER
BY KIRUTHIKA

3. What is a multimeter?
• A multimeter is a devise used to measure voltage, resistance and current
in electronics & electrical equipment
• It is also used to test continuity between to 2 points to verify if there is
any breaks in circuit or line
• There are two types of multimeter Analog & Digital
– Analog has a needle style gauge
– Digital has a LCD display (Referenced during this PPT)

4. Switched
Manually switch between
ranges to get most
accurate reading.
Auto Range
Switches between
ranges automatically for
best reading.
Both of these styles
work the same

5. Meter leads
•Red meter lead
Is connected to Voltage/Resistance or amperage port
Is considered the positive connection
•Black meter lead
Is always connected to the common port
Is considered the negative connection
•Probes
Are the handles used to hold tip
on the tested connection
•Tips
Are at the end of the probe and
provides a connection point

6. Display & Dial Settings
• Meter Dial
Turn dial to change functions.
Turn dial to OFF position after use.
• Panel Indicator
Shows each function and setting
range to turn dial to.
• Probe Connections
Specific for each function.
• Digital Display
Shows measured value.

9. ~ AC Voltage Ground
--- DC Voltage ( Capacitor
Hz Hertz mF MicroFarad
+ Positive m Micro
Negative m Milli
W Ohms M Mega
* Diode K Kilo
))) Audible Continuity OL Overload
Common DMM Symbols
These symbols are often found on multimeter and
schematics.
They are designed to symbolize components and reference
values.

10. • Electronic devices function because of
the movement of invisible electrons.
• The digital multimeter doesn’t make
electrons visible, but it does tell use
what they are doing.

11. • A multimeter is the most commonly used instrument
by technicians and engineers in the laboratory, as
well as other repair works. As it is clear from the
name of this instrument, it can make many (multi)
measurements with reasonable accuracies such as
AC and DC voltages, currents, and resistances.

12. WHAT THE BASIC DMM MEASURE?
• Continuity
• Voltage
• Resistance
• Current

13. • Continuity is a complete current path in a circuit. If there
is continuity, electrons can move from the negative
terminal of the battery, through the circuit, and back to
the positive terminal of the battery.
• Voltage acts like an electrical version of pressure. Voltage
pushes electrons through a closed circuit (one with
continuity). If there is voltage, the electrons flow from
the negative terminal of the battery (like charges repel),
though a conducting path, to the positive terminal of the
battery (opposite charges attract).

14. • Resistance acts like a brake on the movement of
electrons. While voltage tries to make a greater
number of electrons more move through a closed
circuit, resistance tries to keep fewer electrons
moving through the circuit. If there is the proper
amount of resistance in a circuit, electronic
components are protected from damage caused by
too many electrons flowing through them.

15. • Current is the flow of electrons through a closed
circuit. Current is work in a circuit, because electrons
are being moved from one place to another. If there
is current in a circuit, then voltage is pushing
electrons and resistance is trying to limit them.

16. Construction AND Working Principle of
Multimeter
• A multimeter is a permanent magnet moving coil
galvanometer.
• There is an iron cored coil pivoted on two jeweled
bearings.
• The coil is wound on an aluminum former or bobbin. And
this coil is free to rotate in the field of a permanent
magnet.
• An aluminum pointer is attached to the coil and bobbin
assembly and moves on a graduated scale.

17. • There are two spiral springs attached to the coil assembly
at the top and bottom, which provide a path for the flow
of current and controlling torque.
• A multimeter can measure voltage, current, and
resistance for which its galvanometer is converted to a
voltmeter, ammeter, and ohmmeter with the help of
suitable circuits incorporated in it.
• The galvanometer used in a multimeter has always its
pointer resting at zero position on the extreme left end
various measurements are made on a multimeter.

18. Review
• A meter capable of checking for voltage, current, and resistance is called a
multimeter,
• When measuring Voltage the multimeter must be connected to two points
in a circuit in order to obtain a good reading. Be careful not to touch the bare
probe tips together while measuring voltage, as this will create a short-
circuit!
• Never read Resistance or test for Continuity with a multimeter on a circuit
that is energized.
• When measuring Current the multimeter must be connected in a circuit so
the electrons have to flow through the meter
• Multimeters have practically no resistance between their leads. This is
intended to allow electrons to flow through the meter with the least
possible difficulty. If this were not the case, the meter would add extra
resistance in the circuit, thereby affecting the current