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Analog Multi-meters
Vs Digital Multi-meters
Rana T Rehman
ENG 352-005
12-15-2008
Table of Contents
Abstract ........................................................................................................................................... 1
Introduction ..................................................................................................................................... 1
Principle .......................................................................................................................................... 2
Multi-meters History....................................................................................................................... 2
Analog Vs Digital Comparison ....................................................................................................... 3
Conclusion ...................................................................................................................................... 6
References ....................................................................................................................................... 6
Annotated Bibliography .................................................................................................................. 7
Abstract
This article is a comparison of Analog Multi-meter and Digital Multi-meters. Multi-meter
is an electrical measuring instrument. We can measure current, voltage and resistor from
these multi-meters. There are two kind of multi-meter. First of all an Analog Multi-meter
invented. When it invented, it was very huge metal Box. It also got effected easily from
its surrounding magnetic fields. It has so many errors as it affected so quick from its
surroundings. When technology changed from magnetic coil indicator in to Liquid
Crystal Display, the life style changed completely. And this is the time when people think
to change big and heavy multi-meter in to small and compact multi-meter. So, we can get
the values in digits and errorless.
Introduction
Multi-meters are the meters use in electrical measurements. These Multi-meters are very
useful device in electrical engineering. It works on the basic law of Electrical
Engineering. The law used on this meter measurement is a simple Ohm’s Law. From this
Law “Total voltage across the two points in a circuit is equal to the product of current and
resistor inside the circuit” [1]
They are also a multi-tester and sometime known as volt/ohm meter or VOM. It is
one of the basic and very important electric measuring instruments that do several
functions in one unit. The features of a multi-meter or VOM are to measure Voltage,
Current and Resistance.
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Principle
The basic principle of VOM is simply Ohm’s Law. The Ohm’s Law stated that Voltage is
equal to the product of Resistance in the circuit and current flowing in the circuit.
V=IxR
V = Voltage
I = Current
R = Resistor
As we are discussing here the Multi-meter or VOM, that measures Voltage, Current and
Resistor in circuit, I am going to describe these three in Ohm’s Law.
I - Current is what flows on a wire or conductor like water flowing down a river. Current
flows from negative to positive on the surface of a conductor. Current is measured in (A)
amperes or amps.
V - Voltage is the difference in electrical potential between two points in a circuit. It's the
push or pressure behind current flow through a circuit, and is measured in (V) volts.
R - Resistance determines how much current will flow through a component. Resistors
are used to control voltage and current levels. A very high resistance allows a small
amount of current to flow. A very low resistance allows a large amount of current to
flow. Resistance is measured in Ohm’s.
Multi-meters History
There are two categories of multi-meters, analog multi-meters and digital multimeters, also abbreviated as DMM or DVOM. A multi-meter can be a hand-held device
useful for basic measurements of Voltage, Current and Resistor. In electrical engineering,
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these three measurements are extremely important because we can find all faults from
these three measuring in big complicated circuits in industries. This fault finding in
industrial field work can also measure to a very high accuracy. They can also use VOM
to troubleshoot electrical problems in industrial and household devices such as batteries,
motor, appliances, power supplies, and wiring systems.
Figure 1 – Analog Multi-Meter [1]
Analog Vs Digital Comparison
There are many types of multi-meters available with different features and prices. Cheap
multi-meters can cost less than US$10, while the top of the line multi-meters can cost
more than US$5000.The resolution of a multi-meter is often specified in "digits" of
resolution. For example, the term 5½ digits refer to the number of digits displayed on the
readout of a multi-meter. Half digit can display either a zero or a one, while a threequarters digit can display a numeral higher than a one but not nine.
Commonly, a three-quarters digit refers to a maximum value of 3 or 5. The
fractional digit is always the most significant digit in the displayed value. A 5½ digit
multi-meter would have five full digits that display values from 0 to 9 and one half digit
that could only display 0 or 1. Such a meter could show positive or negative values from
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0 to 199,999. A 3¾ digit meter can display a quantity from 0 to 3,999 or 5,999,
depending on the manufacturer.
Figure 2 – Analog Multi-Meter [2]
Digital display can easily be extended in precision; the extra digits are of no value
if not accompanied by care in the design and calibration of the analog portions of the
multi-meter. Meaningful high-resolution measurements require a good understanding of
the instrument specifications, good control of the measurement conditions, and
traceability of the calibration of the instrument. Specifying "display counts" is another
way to specify the resolution. Display counts give the largest number, or the largest
number plus one (so the count number looks nicer) the multi-meter' display can show,
ignoring a decimal separator. For example, a 5½ digit multi-meter can also be specified
as a 199999 display count or 200000 display count multi-meter.
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Figure 3 – Digital Multi-Meter
In the display count is just called the count in multi-meter specifications. In some
designs the underlying analog-to-digital converter mechanism may have more or less
digits of precision than displayed.
A Resolution of analog multi-meters is limited by the width of the scale pointer, vibration
of the pointer, the accuracy of printing of scales, zero calibration, number of ranges, and
errors due to non-horizontal use of the mechanical display. Accuracy of readings
obtained is also often compromised by miscounting division markings, errors in mental
arithmetic, parallax observation errors, and less than perfect eyesight.
They have mirrored scales and larger meter movements are used to improve
resolution; two and a half to three digits equivalent resolution is usual. Resistance
measurements, in particular, are of low precision due to the typical resistance
measurement circuit which compresses the scale heavily at the higher resistance values.
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Conclusion
Multi-meters are still in use but Digital Multi-meter is easy to use and there are less
chances of error there. But Analog Multi-Meter is still effective, and used in some places.
But Analog meters are going to absolute because Digital VOM are becoming more
popular of there small size, less weight, error less and cheap price.
Figure 3 – Fluke Digital Multi-Meter
References
1. “Analog Multimeters – Handhelds Instruments,” Electro-Meters, 5 December 2008.
<http://www.electro-meters.com/Triplett/T_M/AMMs/310_series.htm>.
2. “Analog – VOM Volt-Ohm-Milliammeter”, Simpson 260® Series, 5 December 2008.
<http://www.simpson260.com/260-6/simpson_260-6.htm>.
3."Fluke 289 True-rms Industrial Logging Multimeter with Trend Capture", Find Little Problems
Before They Become Big Ones, 5 December 2008.
<http://us.fluke.com/usen/products/Fluke+289.htm?trck=289>.
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Annotated Bibliography
“Analog Multimeters – Handhelds Instruments,” Electro-Meters, <http://www.electrometers.com/Triplett/T_M/AMMs/310_series.htm>, Accessed Dec 05, 2008.
This is an article that is exactly what I was looking for – it will supply me with data that I
need for old Analog Multi-meter. This is a very useful website but there is no listed
author and it is in company website, the company that make one of multi-meter I am
describing in my research that has a lot of information. I am sure the information
provided on this site is good and authentic because this product belongs to same
company. Also, since it is from a company website, it has a greater chance of being true
than if it were in an advertisement But I don’t know why they didn’t mention author
name. May be there is more then one author or whole group of people that belong to a
company’s department. It has right information as I needed for this research and that’s a
lot of information, but I’m not sure I will use all of it. However, some of the illustrations
are good.
“Analog – VOM Volt-Ohm-Milliammeter”, Simpson 260® Series ,
<http://www.simpson260.com/260-6/simpson_260-6.htm>, Accessed Dec 05, 2008
This is a website that will supply me with data that I need for Simpson 260 Analog Multimeter. The company that makes one of multi-meter I am differentiating in my research
that has a lot of information. I am sure the information provided on this site is good and
true because this product belongs to same company. May be there is more then one
author/engineer or whole group of that company’s department that’s why they didn’t
include author name in this website. It has right information as I needed for this research
and that’s a lot of information, but I’m not sure I will use all of it. However, some of the
illustrations are good. It also has images that I can use in the proposal.
Ebay Website, < http://cgi.ebay.com/New-Model-310-C-Triplett-Analog-VOM-Multimeter3022_W0QQitemZ250200081519QQcmdZViewItem#ebayphotohosting>, Accessed Dec. 5,
2008.
This is a store-type website that I am going to use in my proposal because it has some
pictures that is required in my topic to explain briefly. It also has images that I can use in
the proposal. I will also use the price listed in my proposal.
Ebay Website, < http://cgi.ebay.com/SIMPSON-260-SERIES-6-VOM-METER-VOLT-OHMMILLIAMMETER_W0QQitemZ260327253849QQcmdZViewItemQQimsxZ20081205?IMSfp=
TL0812051210001r15345>, Accessed Dec 5, 2008
This is a commercial store-type website that I am going to use in my proposal because it
has some pictures that is required in my topic. It also has images that I can use in the
proposal. I will also use the price listed in my proposal.
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"Fluke 289 True-rms Industrial Logging Multimeter with Trend Capture", Find Little Problems
Before They Become Big Ones, <http://us.fluke.com/usen/products/Fluke+289.htm?trck=289>,
Accessed Dec 5, 2008.
This is the website of the one of the leading company in measuring instrument industries
in Electrical Engineering. They provide the best instrument with latest technology in our
modern world where every calculation and observation makes a difference of millions of
dollars in big contracts. The information I received from this website is absolutely correct
as they are the inventors of digital measuring instrument industries. I got all information I
needed from this company website as they are so much concerned to demonstrate there
product in well organized manner. I had all information about description, pictures,
specifications, working environment, and interfacing option with it’s price, all in same
website.
“The Application Guide”, Ohm’s Law, <http://www.the12volt.com/ohm/ohmslaw.asp>,
Accessed Dec 6, 2008.
This site has most of the definition used in my article. As I am studying electrical
engineering and I am in senior year. I have these definitions in my head. So, I can see my self
that these definitions are right and very well defined. That’s the reason I use this site as a
reference to my work to you.
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