4 bit Asynchronous Counter with J K Flip Flop - YouSpice
flipflop - Why use JK Flip Flops in syncronous/asyncronous binary counters rather than D flip flops? - Electrical Engineering Stack Exchange
How to design a synchronous counter 4 bit using JK flip flop that can count up even numbers from 0 to 14, and count down odd numbers from 15 to 0 in 1 system - Quora
Is it possible to design a 3 bit down counter using JK flipflop? - Quora
Synchronous Counter and the 4-bit Synchronous Counter
Synchronous Counter and the 4-bit Synchronous Counter