Tuesday, September 30, 2008

Electronics Tech Questions

What is D-FF?

D-FF stand for Delay-type Flip-Flop.Its a logic gate used in logic design n perform various functions.its truth table is as follows:
A o/p
1 1
0 0
output is same but just delayed it has one input n only one output

What is the basic difference between Latches and Flip flops?

Latch is a level triggered device whereas a flip flop is edge triggered. latches and flip-flops are the building blocks of sequential circuits. While gates had to be built directly from transistors, latches can be built from gates, and flip-flops can be built from latches. This fact will make it somewhat easier to understand latches and flip-flops.

Both latches and flip-flops are circuit elements whose output depends not only on the current inputs, but also on previous inputs and outputs. The difference between a latch and a flip-flop is that a latch does not have a clock signal, whereas a flip-flop always does.

Latches are asynchronous, which means that the output changes very soon after the input changes

A flip-flop is a synchronous version of the latch

What is sampling theorem ?

Sampling frequency should be twice the highest frequency component in the signal to be measured.

However, samples recieved in this manner are good only for finding the values of the signal and cannot be used for reconstructing the signal shape. That would require many more times the sampling frequency as defined above.

What is a multiplexer?

Multiplexer is “many to one” kind of switch ther r many inputs n allows only one out at a time based on its status lines.
status lines decides which input to be connected to output.

Which type of modulation is used in TV transmission?

In TV transmission FM(frequency modulation) is used for the sound signal and AM(amplitude Modulation) is used for the picture VSB can be used to reduce the bandwidtg for video signal whose BW can reach 4.5 MHZ so in stead of using 9 MHZ as in AM we can use only 6 MHZ and it is easier to implement than than SSB which requires a sharp filter that can be parctically found in AM

Courtesy : Surya, ECE, LBSITW, TVM


  1. Pls try 2 Put sum more qns and their solns.

  2. sree..............October 2, 2008 at 4:11 PM

    really nice add more tech ...... related to electronics so thet it may help even students from s1s2