Electronics and Communication Engineering - Digital Electronics

31. 

In which counter does the maximum frequency depend on the modulus?

A. Synchronous
B. Ripple
C. Both synchronous and ripple
D. Neither synchronous nor ripple

Answer: Option B

Explanation:

Since propagation delays of all flip-flops are added in ripple counter, the maximum frequency depends on the number of flip-flops which depends on modulus.


32. 

A current tracer responds to

A. steady current only
B. pulsating current only
C. both pulsating and steady current
D. none of the above

Answer: Option B

Explanation:

The indicator of current tracer glows when its tip is held over a pulsating current path.


33. 

A presettable counter with 4 flip flops can start counting from

A. 0000
B. 1000
C. any number from 0000 to 1000
D. any number from 0000 to 1111

Answer: Option D

Explanation:

Since 4 flip-flops are used it can count from 0000 to 1111. By presetting it can start from any number.


34. 

A logical expression Y = A + AB is equal to

A. Y = AB
B. Y = AB
C. Y = A + B
D. Y = A + B

Answer: Option D

Explanation:

Y = A + A B = (A + A) (A + B) = (A + B).


35. 

Using the same flip flops

A. a synchronous flip flop can operate at higher frequency than ripple counter
B. a ripple counter can operate at higher frequency than synchronous counter
C. both ripple and synchronous counter can operate at the same frequency
D. can not determine

Answer: Option A

Explanation:

In a synchronous counter clock pulses are applied to all flip-flops simultaneously. Hence minimum time delay and high frequency.