Q1.Which of the following is an invalid state in an 8-4-2-1. Binary Coded Decimal counter
Answer : Option DExplaination / Solution:
In binary coded decimal (BCD) counter the valid states are from 0 to 9 only in binary system 0000 to 1001 only. So, 1100 in decimal it is 12 which is invalid state in BCD counter.
Q2.A 10 kHz even-symmetric square wave is passed through a bandpass filter with centre frequency at 30 kHz and 3 dB passband of 6 kHz. The filter output is
Answer : Option CExplaination / Solution:
10 KHz even symmetric square wave have frequency component present 10KHz, 30KHz, 50KHz, 70KHz
[only odd harmonics due to half wave symmetry]
Since bandpass filter is contered at 30KHz, 30KHz component will pass through
filter output is nearly perfect cosine wave at 10 KHz
Cosine in due to reason that signal in even signal.