Testbook Test Series: Digital Logic - Digital Counter

Question

A ripple counter with J-K flip-flop can be made to count down rather than up by

 i. Connecting the Q dash output to the input of the next stage, rather than the Q output

ii. Making the output transition to occur at the rising edge rather than the falling edge

iii. Designing a logic circuit that inverts the output of the counter

iv. finding the two's complement of the output.

 

According to me, the answer should be ii but the answer given in iii which also make sense as just inverting the outputs will count down because for up counter the output will be 0,1,2,3.... and if we invert the binary output of each gate then the count is reversed.

Comments

vinay chauhan 2nd option will not change anything in output it will still be an up counter

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But from the comments in https://gateoverflow.in/249042/digital-logic, it is possible by option 2, right?

Answer 1

With rising edge of the clock  and making transition will give both UP counter and Down counter.When the next stage clock is connected to Q then Down counter but if connected to Q dash it gives UP Counter.So option (iii) is correct.