9 aei105.4
-
Upload
srinivas-rao -
Category
Engineering
-
view
38 -
download
1
Transcript of 9 aei105.4
9AEI105.4 1 1
DEPARTMENT OF TECHNICAL EDUCATION ANDHRA PRADESH
Name : P.S.R. Muralidhar Designation : Sr. Lecturer in ECE Branch : Electronics & Comm. EngineeringInstitute : G.M.R. Polytechnic, GajwelSemester : I YearSubject : Basic Electronics Sub. Code : AEI1-105 Topic : ResistorsDuration : 50 minSub Topic : Preferred values in resistorsTeaching aids : Diagrams, animationsRevised by : N.Venkateswerlu Lecturer in ECE
9AEI105.4 2 2
Objectives
On completion of this period, you would be
able to know about
• Preferred values in Resistors.
9AEI105.4 3 3
Recap
We see Resistors of different values
Is a 10 Ω Resistor available ?
• Yes
Is a 25 Ω Resistor available ?• No
So Resistors of all values are not available
9AEI105.4 4 4
Preferred values in Resistors
What is meant by Preferred values in Resistors ?
• The resistance values of commercially available
resistors.
• The electronic industry specified some preferred values
to be manufactured at different wattages.
9AEI105.4 5 5
Why only certain value Resistors available?
• Not possible to manufacture all values of Resistors from
1Ω to several MΩ.
• Not possible to adjust every Resistor to an exact value.
9AEI105.4 6 6
• Only certain values of Resistors are made in each
Tolerance range
• Usual Tolerance ranges are
5%, 10%, 20%
• Precision Resistors may have Tolerances as low as 0.1%
(Contd…)
9AEI105.4 7 7
• A 100 Ω Resistor with 20% tolerance may have
any value from 80 Ω to 120 Ω
• A 100 Ω Resistor with 0.1% tolerance will have a
value between 99.9 Ω to 100.1 Ω.
(Contd…)
9AEI105.4 8 8
Commercially Available Preferred Values of Resistors
Tolerance Preferred values ( in Ω )
5% 10,11,12,13,15,16,18,20,22,24, 27,30,33,36,39,43,47,51,56,62, 68,75,82,91,100
10% 10,12,15,18,22,27,33,39,47,56, 68,82,100
20% 10,15,22,33,47,68,100
9AEI105.4 9 9
• The above table indicates the available Resistors in 10 Ω to 100 Ω range.
• Resistors with all their multiple and sub-multiple values are also available.
Ex. 4.7 Ω, 47 Ω, 470 Ω etc. are available
9AEI105.4 10 10
Summary
• Resistors of all values are not available
• Only a set of Resistor values called Preferred values of
Resistors available
• Different Preferred values of Resistors are available in
different tolerance ranges.
9AEI105.4 11 11
Quiz
• Which of the following is preferred value in 10% tolerance
a) 15 Ω
b) 35 Ω
c) 45 Ω
d) 65 Ω
9AEI105.4 12 12
Frequently Asked Questions
1. What is meant by Preferred values Resistors ?
2. List some commercially available Preferred value
Resistors.
9AEI105.4 13 13
Assignment
• Take any 10 resistors in your laboratory and check
whether those resistors are in the preferred values or
not?