Basic Electronics

***************************************************************************

Basic Electronics Test 3-2007

Part A:

1  a)   Convert from decimal to binary:    11.125                                                              -2-

    b)   Convert      (3576)₈ to hexadecimal                                                                       -2-

     c)    Subtract (11101)₂ from (101011)₂ using 2’s complement method                           -3-

     d)   Prove that

                               AB+A+AB =0                                                                               -3-

2 a)  Realize the following expression using basic gares:       AB+A+(B+C)                      -3-

    b) Explain the operation of full adder with a truth table and implement it using logic gates  -5-

     c)  Implement the expression   Y=AB+AB using                                                        -2-

                      i) only NAND gates

                      ii) only NOR gates.

Part B

3 a)  Constuct a truth table for the following expression   f=C(B+D)                                 -3-

   b)  Implement F= (A+BC)(A+B+C)(A+B) using only NAND gates                              -3-

    c) Convert (2604.10546875)₁₀ to hexadecimal                                                             -2-

    d) Write the Boolean expression for the following logic diagram                                   -2-

4 a)  Perform I’s complement and 2’s complement subtraction on the following.

                (1001101)₂ -  (1001001)₂                                                                                -2-

    b)  Simplify using De Morgan’s theorem   ABCD                                                        -2-

    c) Implement using only NOR gates  Y=(A+B+C)(A+B+C)(A+B)                              -3-

    d)  Simplify and implement using gates Y= (A+BC)(A+B+C)                                                   -3-

Part C

5 a) For an AM system, amplitude of modulating signal is 0.5 V and carrier amplitude is 1 V.  

       Find modulation index.                                                                                            -2-

   b)  Derive the expression for the instantaneous voltage of amplitude modulated wave.    -3-

6 a) A carrier of 500w, 1 MHz is amplitude modulated with a sinusoidal signal of 1 KHz,

       depth of modulation is 60%. Calculate bandwidth, power in the sidebands and total power 

       transmitted.                                                                                                            -3-

   b) The maximum and minimum amplitudes of an AM wave are 600mV and 200 mV

       respectively. Find the modulation index.                                                                   -2-

_{**************************************************************************}