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Archive for March, 2011


A multiplexer is a circuit which has many inputs but only one output. Multiplexer  or MUX means many into one. By applying proper control signal we can steer any input to the output. Therefor it is also known as data selector and control inputs are called select inputs.

Watch this ppt on Multiplexer

MUXBlockDia gives the general idea of MUX. m control signal can select maximum 2 rest to m input signals and therefore n should be less than or equal to 2 rest to m.

Go through 4-to-1 Multiplexer

Click on this Image for Multiplexer Animation

As shown in the circuit diagram ‘a‘ (or A) and ‘b ‘(or B) are control inputs, A (or D0),B(or D1),C(or D2).D(or D3) are data inputs and Q (or Y) is output.

First end gate will give output of a’b’A(0r A’B’D0), second a’bB(or A’BD1), third ab’C(or AB’D2) and fourth abD(or ABD3) and these output will be given to ‘OR’ which will give output as




From above equation, suppose control inputs a (or A) =0 and b (or B)=0 then




Therefore Q or Y =1.1D0+1.0D1+0.1D2+0.0D3

Q or Y =D0

Similarly, for control inputs ab or AB =00 the first AND gate to which D0 or A is connected will activate and its output is D0 and all other AND gates are inactive with zero output. Thus Q or Y output with ab or AB=00 will be D0. If D0=0 then output will be zero and if Do=1 output will be 1.

Same way, for ab or AB =01, the Q or Y output will be D1. In a similar manner we get the following truth table

Control Inputa or A                  b  or  B OutputQ or Y
0                               0 Do or A
0                               1 D1 or B
1                               0 D2 or C
1                               1 D3 or D

More clearly go through this ppt

  • Watch video on Multiplexer Based Design.

Combinational Logic-Multiplexer

Summary: Must go through this page of MUX


Q.1    How many control inputs are required for 5-to-1 MUX?

Q.2. Give the type of commercial ICs of multiplexer.

Q.3   Send link of 16-to-1 multiplexer with its output Y equation

and explain its operation in brief.

Q.4   Draw the pinout diagram of 74150 of multiplexer IC and

describe its function with truth table?

Q.5 Can we design multiplexer using OR gates in place of AND and AND gate in place of OR?

Q.5  Go to this link of Multiplexer Applet(on right  top and click on multiplexer) and explain the operation of MUX circuit  with its truth table in excel sheet?

Q.6 Go to this Learning Object of Multiplexer and answer the four questions given in it.

Q.7 Search the link of MUX  tutorial(at least 5 other than used already) and its ICs relevant to our syllabus.

Q.8 Search the ppts and pdf of MUX other than used here.

Q.9 Give links of MUX video and audio relevant to our syllabus.




Data-Processing Circuits


Data is information that has been translated into a convenient form to process   Data-Processing circuits are logic circuits that process binary data. Such logic circuits may be Multiplexer(also known as MUX), De=Multplexer, Encoder, Decoder or Exclusive-OR Gate.

Time: 5 hours

Level : Third Year B.Sc.


  • Decide the output of a multiplexer or demultiplexer based on input conditions.
  • Find out the output of an encoder or decoder from input conditions.
  • Sketch the symbol and explain the operation of Exclusive-OR gate.

Learning Outcomes:

By the end of this unit you should be able to :

  • Describe the operation and truth table of  Multiplexer.
  • Explain the function of IC-74150(16 to 1 Multiplexer)  and Multiplexer Logic.
  • Analysis of Universal Logic Circuit.
  • Discover the functioning of demultiplexer with its IC-74154.
  • Outline of 1-of-16 decoder using IC-74154.
  • Describe the operation of encoders and exclusive-OR gates.

Game Changer for Educators

A Day in the Internet
Created by Online Education” />

“The times they are a-changing”

By Bob Dylan

The most overused yet most relevant quote on earth.The times they are continuously changing and even in nature  from atom to universe everything is changing. Nothing is static in this universe except  few universal things like “The best teaching is always built upon relationship”.Osho said ‘Static’ is one of the delusive word in the dictionary. So change is only constant.

Lets learn ‘how changing survives’ from the story of the Eagle.

So change is must in a positive direction to survive.