INTRODUCTION

A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is

an electronic measuring instrument that combines several measurement functions in one unit. A

typical multimeter would include basic features such as the ability to measure voltage, current,

andresistance. Analog multimeters use a microammeter whose pointer moves over a scale

calibrated for all the different measurements that can be made. A multimeter can be a hand-held

device useful for basic fault finding and field service work, or a bench instrument which can

measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems

in a wide array of industrial and household devices such as electronic equipment, motor

controls, domestic appliances, power supplies, and wiring systems.

Title : Analog multimeter and application

Objectives : At the end of this experiment, student should be able to

i. Do the measurement by using analog multimeter

ii. Give knowledge about the usage of analog multimeter and its

function.

iii. Practice how to read the scale and set the range of multimeter

Equipment List

i. Analog Multimeter

ii. Variable DC power supply

iii. Bread board

iv. Resistor

v. Wire clip

THEORY

Multimeter are very useful test instruments. There are two type of multimeter : Analog multimeter

and digital multimeter. Analog meters use the force within the circuit to move a pointer to a scale

position. Digital meters sense the force within the circuit and convert it to an ordinary number.

By operating a multi-position switch on the meter they can be quickly and easily set to be a

voltmeter, an ammeter or an ohmmeter. In other words, this instrument is used to measure

resistance, current and voltage in electric circuit. It is also used to test electronic component such as

resistor, capacitor, inductor, diode, transistor and etc. Besides, we can check the condition of these

components whether good or not.

If we looked at the analog multimeter, this equipment is classified into 6 basic division :

a) Control unit

Control unit can be set followed by measurement unit as we need. For Example, if we want

to measured alternating voltage and current ( AU / AC ), we must set the control unit to

AVC ( alternating current voltage ) and so on.

b) Reading Scale

Reading scale has several curve line with certain unit such as DCV.A, AVC,Ω and so on.

Electric quantity is measured in this meter by the reading scale.

c) Pointer

The pointer is moving on the reading scale to show you the value of the electric quantity

being measure.

d) Terminal Meter

There ae two terminal meter named positive and negative terminal. Both of terminal are

joint to test lead where as the red colour for positive terminal and black colour for negative.

e) The pointer-zere adjustment ( only for analog multimeter )

It is used to set the scale of volt and current on zero. An adjustment is not required if the

pointer is set to zero.

f) The ohms-zero adjustment ( only for analog multimeter )

Along the bottom of the meter panel marked as ohms zero. This knob is used to set the full

scale deflection of the pointer whenever the function is set to ohm. Full scale is usually zero

ohms. To set this :

I. Set function to ohms

II. Set range to R × 1

III. Touch probes together

Label of Each Indicator on the analog multimeter

Measurement method of analog multimeter

Analog meters take a little power from the circuit under test to operte their pointer. They must have

high sensitivity of at least 20 kΩ / V or they may upset the circuit under test and give an incorrect

reading.

Batteries inside the meter provide power for the resistance ranges, they will last several years but

you should avoid leaving the meter set to a resistance range in case the lead touch accidentally and

run the battery flat.

Typical ranges for analog multimeters like the one illustrated in figure : 1.1

( the voltage and current value given are the maximum reading on each range )

DC Voltage : 0.5V, 2.5V, 10V, 50V, 250V, 1000V.

AC Voltage : 10V, 50V, 250V, 1000V.

DC current : 50µA, 2.5mA, 25mA, 250mA.

A high current range is often missing from this type of meter.

AC current : None. ( you are unlikely to need to measure this )

Resistance : 20Ω , 200Ω, 2kΩ, 20kΩ, 200kΩ

These resistance value are in the middle of the scale for each range.

If we looked at the reading scale of multimeter, we will see many colorful curve lines. Every line is

used for certain unit such as resistance ( Ω ), direct voltage and current ( DCV.A ), alternating

curret ( ACV ) and so on ( see figure 1.2 ).

Figure 1.2

A. Resistance Measurement

The resistance scale on an analog multimeter is normally at the top, it is an usual scale

because it reads backwards and is not linear ( evenly spaced ). This is unfortunate, but it is

due to the way the meter works.

1. Set the meter to a suitable resistance range.

Choose a range so that the resistance you expect will be near the middle of the scale.

For example : with the scale shown below and an expected resistance of about 50 kΩ

choose the × 1kΩ.

2. Hold the meter probes together and adjust the control on the front of the meter

which is usually labeled “ 0Ω ADJ ’’ until the pointer reads zero (on the right

remember ! )

If you can adjust it to read zero, the battery inside the meter needs replacing.

3. Put the probes across the component.

Avoid touching more than one contact at a time or your resistance will upset the

reading !

Choose scale range at × 1Ω. When the pointer shows at 20 scale reading, therefore

the total of resistance is 26 × 1Ω = 26Ω

B. DC Voltage Measurement

There are 3 ranges in this scale reading : 0 to 10, 0 to 50 and 0 to 250.

When you want to measure a voltage not more than 50V, the suitable scale Range is 0 to

50V. For example, if the pointer shows at 20, the total of Voltage measured is 20V

If the voltage is around 0.1V, so suitable scale reading is 0 to 10V ( 10/100=0.1V ). For

example, if the pointer shows at 8, the total of voltage measured is 8/100 = 0.08V.

C. DC Current Measurement

Scale range has been choosing is 25 mA. The suitable scale reading is 0 to 250 ( 250/10 =

250 mA ). If pointer at 150, the total of current measured is 150/10 = 15 m

Taking accurate reading

To take an accurate reading from an analogue scale you must have your eye in line with the pointer.

Avoid looking at an angle from the left or right because you will see a reading which is a little too

high or to low. Many analogue meters have a small strip of mirror along the scale to help you.

When your eye is in the correct position the reflection of the pointer is hidden behind the pointer

itself. If you can see the reflection you are looking at an angle.

Precaution

Multimeters are easily damaged by careless use so please take these steps :

Always disconnect the multimeter before adjusting the range switch.

Always check the stting of the range switch before you connect to a circuit.

Never leave a multimeter set to a current range ( expect when actually taking a reading ) .

The greatest risk of damage is on the current ranges because the meter has a low resistance.

Experiment 1 – 2 : Reading of Analog Multimeter

PROCEDURE

1) DC Voltage Reading ( unit volt )

i. Ensured the positive prove ( red ) in positive ( + ) terminal and negative probe ( black )

in negative ( - ) terminal

ii. Select the selector to DCV in 250 DVC

iii. Look the black colour scale

and find the maximum scale. The maximum scale at point 1 ( 250 ) based on selector

value 250 DVC.

iv. Look the scale at point 2 and take the reading.

v. The reading shows at 100 V in volt DC unit.

2) Resistor value reading ( unit Ω )

i. Ensured the oisitive prove ( red ) in positive ( + ) terminal and negative probe (black)

in negative ( - ) terminal.

ii. Before make reading the resistor measurement at the selector switch of analog

multimeter, the best practice touch two probe positive and negative and make 0Ω

adjustment for resistor measurement.

iii. Example : select the selector to Ω range at ×100

iv. Look at top of black colour scale and find the number in Ω base from the right at 0Ω

v. Lokk scale at point 1 and take the reading of scale

vi. The reading shows at 10Ω ( multiply ) the value at the scale ( 100Ω )

vii. The final result = 1kΩ in Ω unit.

3) AC volt reading ( unit volt )

i. Plug the red test lead into the output socket and the black one into the –com

ii. Set the range selector at the selected range position

iii. Example : Select the selector in ACV range at 50

iv. Look the black colour scale and find the maximum scale. The maximum scale at

point 1 ( 50 ) based on selector value 50 AVC

v. Look the scale at point 2 and take the reading.

vi. The reading shows at 41 V in AC volt unit.

4) DC ampere reading ( unit mA )

i. Placed the red test lead into + socket and the black into the –COM for DCA range at

50 µA – 250 mA

ii. Placed the red test lead into the DC 10A MAX socket and the black into –COM for

DCA range at 250 mA – 10A

iii. Set the range selector at a selected DCA range position

iv. Example : select the selector to DCmA range in 250

v. Look the black colour scale and find the maximum scale. The maximum scale at

point 1 ( 250 ) based on selector value 250 DCV.A

vi. Look the scale at point 2 and take the reading.

vii. The reading shows at DC current at 155 mA unit.

Experiment 2 – 2 : Measurement Of Analog Multimeter

Procedure :

i. The circuit was connected as shown as figure1.4 ( a ), ( b ) and ( c ) . The resistor was

choosen by ourself and the equipment was used as list provided.

ii. The method of analog measurement was used as mention before.

iii. The measurement was listed down into table 1.1

iv. The calculation was done for V / I and was listed down into table 1.1

v. The above instruction was repeated for the other 4 resistor

Measurement calculation Colour

code No. R (ohm ) V ( Volt ) I (Ampere ) V / I

R1

(3 type ) 16 Ω 10 V 365 mA 27.4 Ω

Coklat hijau hitam emas

1 5 1 5 %

R2

55.8 Ω 10 V 147.7 mA 67.7 Ω

Hijau biru hitam emas

5 6 1 5%

R3

49 kΩ 10 V 0.21 mA 47 619 Ω

Kuning ungu oren emas

4 7 1k 5%

R4

3.5 kΩ 10 V 2.77 mA 3 610 Ω

Oren biru merah emas

3 6 100 5%

R5

7.8 kΩ 10 V 1.31 mA 7 633 Ω

Ungu hijau merah emas

7 5 100 5%

Table 1.1

vi. The simple circuit shown below was constructed on the breadboard with one of the resistor

whose resistance measured above. The supply voltage was set to 3V DC.

Vii. Turn the multimeter dial to the appropriate (voltage) setting.

Viii. Supposed that want to measure voltage diference Va-Vb. To actually make the makesurement,

touch the black lead to point B and touch the red lead to point A.

Ix. Record the measured voltage : 3.0 VDC.

X. Perform and record the following measurements :

a. VC – VA ; why is this voltage different zero ?

Because this is parallel circuit, and in the parallel circuit the voltage across each

component in the circuit is the same. Voltage through each component is equal to the

amount of voltage supplied by the power source in the circuit.

b. VB - VA ; why is this voltage different negative ?

In thi situation this concept same like parallel circuit at (a) but the different negative

voltage because the probe reversed its connections at the circuit of negative to positive,

while postive to negative.

DISCUSSION

1. Reading on the scale.

Based at pointer on the scale of multimeter, write the reading value at the every range below :

RESULT :

Selector Range Reading Unit

DCV 50 9V VOLTAN (V)

DCV 2.5 2.9V VOLTAN (V)

DCA 0.25 0.45A AMPERE (A)

Resistor ×1 Ω 95 Ω OHM (Ω)

Resistor ×1 KΩ 95KΩ OHM (Ω)

ACV 1000 30V VOLTAN (V)

2. Measurement of analog multimeter

A. Compare the value of V / I with R

Based on the table 1.1, is there any different value ? if yes, please explain.

Yes, based in table 1.1 the value of R is difference between V/I and compare with

multimeter reading. This problem happen because of an error in the doing of

experiments. In addition, the multimeter set to the correct position is also an important

role in addition to reading mutimeter correctly.

B. Analog multimeter can check the condition of components whether good or not. Discuss on

how to check the condition of switch and fuse.

Switch

To perform this method correctly, you will need to apply this method in both cases

(ON & OFF positions) on switches and push buttons…In other words, first apply

this method on switches/push buttons and then “Push” the push button and perform

the same method again. At first attempt, if meter reading is “Zero” and in the

second attempt, the meter reading is infinite, it means Switch/Push button is in

good condition. If Multimeter reading is “Zero” or “infinite” in both attempts, it

means switch is in short circuit or continuity connection is broken and you should

replace it with a new one

Fuse

To verify Fuse condition, We perform the same method I.e. continuity test as

mentioned above. In short, if the meter reading is “Zero” it means Fuse is in good

condition. If Multimeter reading is infinite, it means Fuse continuity may be

broken or blown. So you should replace it with a new one immediately.

C. The multimeter is not suitable to measure capacitor with the low capacitance value.

Thus, define the suitable equipment to measure it.

multimeter for measuring capacitor is not suitable. financing tool used is the digital

capacitor meter, it is the most suitable because there is a fuse that prevents the meter

was broken. Moreover the equivalent series resistance (ESR) of real capacitors;

usually without the need to disconnect the capacitor from the circuit it is connected

to. Other types of meter used for routine servicing, including normal capacitance

meters, cannot be used to measure a capacitor's ESR, although a few combined

meters are available which measure both ESR and out-of-circuit capacitance.

D. Discuss the advantages using Digital Multimeter than Analog Multimeter

Here are the main points of comparison between the two.

In analog multimeters, visual indication of changes in the reading is not good due to the

effect of damping torque. Whereas in a digital multimeter, an excellent visual indication of

changes in reading is acquired.

Analog multimeters are accurate, but not as much as the digital multimeter due to the

magnetic effect in the coil being degraded after usage. Digital multimeters are highly

accurate compared to analog.

An analog multimeter is less costly compared to the digital counterpart due to a simple

construction and no power supply being required. But in the case of a digital multimeter, it

is far more expensive than the analog multimeter and has a complicated construction, and

also requires a power supply.

In an analog multimeter, the range has to be adjusted by the user. Whereas in a digital

multimeter, the range is adjusted automatically.

In a digital multimeter, the mechanical handle can be easily rotated to tune the circuit to its

peak.

CONCLUSION

Multimeters are very cheap tools for the number of functions that they provide. It's generally

worthwhile buying one that has all of the functions you need and then looking after it. For the

conclusions that can be derived from these experiments is how the correct way to use a multimeter,

and a method of reading the multimeter correctly besides position selector terminals multimeter

correctly and accurately. In addition, we can also prevent damage to the equipment by placing the

right range.

REFERENCES

http://www.repairfaq.org/REPAIR/F_semitest.html

http://www.repairfaq.org/sam/captest.htm

http://en.wikipedia.org/wiki/ESR_meter

http://circuit-zone.com/?cat=test_and_measurement

http://www.brighthubengineering.com/diy-electronics-devices/94131-digital-and-analog-

multimeters-which-is-best-to-use/