This document discusses the parts and proper use of a volt-ohm-milliammeter (VOM) or multimeter. It identifies the key parts of a VOM/multimeter including the pointer/needle, ohmmeter scale, range multiplier, zero ohm adjustment, and test probes. Safety precautions for using a VOM are outlined such as always setting the function switch to a voltage higher than expected and storing the device in a dry, cool place away from magnets. The document also provides objectives and questions to help understand the purpose and identify parts of a VOM/multimeter.

1. ANDY B. CATUBIG
TLE ELECTRONICS 9

4. PARTS OF
OHMMETER

5. 3. Demonstrate the proper steps of using Volt-Ohm-
Milliammeter (VOM) or Multimeter.
OBJECTIVES
1. Understand the purpose of Volt-Ohm-Milliammeter
(VOM) or Multimeter.
2. Identify the parts and function of Volt-Ohm-
Milliammeter (VOM) or Multimeter.

6. VOLT-OHM-MILLIAMMETER
OR MULTIMETER
• It is an equipment that combines three
functions: as a voltmeter that measures both ac
and dc voltages; an ohmmeter that measures
resistance; and milliammeter that measures
small amount of dc current. As safety
precautions in the maintenance of this
instrument, the following should be observed:

7. • 1. Always rest the function switch at 250V AC, if an OFF
position is not available in the instrument.
VOLT – OHM - MILLIAMMETER
• 2. For current and voltage measurements, always set the
function switch in the correct setting which is a little higher
than the expected current or voltage present in the circuit.
• 3. Place the instrument in a cool dry place, away from any
magnetic devices, and free from vibrations.

8. Ohmmeter is a measuring
instrument used to determine the
resistance of a component or
equipment. This instrument is a
great help in knowing the actual
resistance of the resistors.
OHMMETER
The commonly used ohmmeter in
electro-electrical laboratories now
nowadays is embedded in a multi-
function testing instrument called the
(Volt-Ohm-Milliammeter) VOM. For this
discussion the VOM will be used but
confined only to the ohmmeter section.

9. It is the most important part of the ohmmeter. It
indicates the value of electrical quantity that has
been measured.
POINTER OR NEEDLE.

10. Nonlinear scale where reading of the resistance is
based. It is usually found in the uppermost part of
the VOM.
OHMMETER SCALE

11. The portion of the ohmmeter where the actual
reading is being multiplied.
RANGE MULTIPLIER

12. It is the portion of the ohmmeter where it is adjusted
when the pointer of the ohmmeter fails to point to zero.
ZERO OHM ADJUSTMENT

13. Serves as the input portion of the ohmmeter. Red test
probe becomes positive in some instances, while the
black one is negative.
TEST PROBE

14. This is the zero collector whenever you calibrate, the beginning as
0 voltages both the AC and DC measurement. Use your flat screw
driver to set this knob to calibrate the 0 voltages of your tester. The
name alone as Infinity knob because 0 voltage region of the tester
is the infinity region of the resistance.
THE DIAL OR THE INFINITY KNOB

16. 2. What are the parts of an ohmmeter?
QUESTIONS TO ANSWER:
3. What are the safety precautions in using VOM?
1. What is VOM?

17. Give one part of an ohmmeter and tell
something about its function.

18. Word Search!
Encircle the words related to multimeter.
1. Multimeter
2. Probe
3. Ohmmeter
4. Pointer
5. Ohms

19. Give an example of electronics equipment
and its function write it in a ½ sheet of pad
paper.
ASSIGNMENT

20. Thank you
and
God bless