4-bit Binary Up Counter JK Flip-Flop - Multisim Live
Binary Counter
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
Bidirectional Counter - Up Down Binary Counter
Synchronous counter
flipflop - Why use JK Flip Flops in syncronous/asyncronous binary counters rather than D flip flops? - Electrical Engineering Stack Exchange