DIGITAL ELECTRONIC (ANSWER) Quiz 2a

DIGITAL ELECTRONIC

Quiz 2a (10 marks)

1.       State 2 (TWO) differences between asynchonous and scynchonous counter.   (4 marks)

Number	asynchonous counter	Scynchonous counter
1	Clock- from previous ff	Clock – connect simultaneously
2	Build- easy	Build- complex
3	Can use ff T and JK	Can use ff T,D and JK
4	propagation delay increase if ff increase	No propagation delay

Either 2 (2x2 marks)

2.       Build modulo-12 ascynchonous counter. The steps should be cleared, the truth table must be included.                                                                                                            (10 marks)

Table: 12-modulo counter
D	C	B	A
0	0	0	0
0	0	0	1
0	0	1	0
0	0	1	1
0	1	0	0
0	1	0	1
0	1	1	0
0	1	1	1
1	0	0	0
1	0	0	1
1	0	1	0
1	0	1	1
0	0	0	0

 

3.       The modulo-14 ascynchonous counter has 5kHz input frequency. Calculate the output frequency.                                                                                                            (3 marks)

f_out   =   f_in/ mod =  5x10³/14   =  357.14Hz

4.       What is value of counter  (its modulo) if two decade counters (0-9) are  connected in cascaded.                                                                                                          (3 marks)

Modulo = 10   x   10   =    100

Count from 0 to 99