# HELP understanding JK circuit

Discussion in 'Homework Help' started by DaffyD, Sep 24, 2008.

1. ### DaffyD Thread Starter New Member

Sep 24, 2008
3
0
I don't understand how a JK flip flop series works. There is a series of 4 circuits all attached to a clock. The starting value is 0000.

I need to trace it and tell what it does. Diagram is attached.

• ###### JK flip flop series.JPG
File size:
24.6 KB
Views:
25
Last edited: Sep 24, 2008
2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hint: what will be the state of the Q and ^Q outputs at the initial state?

Last edited: Sep 24, 2008
3. ### DaffyD Thread Starter New Member

Sep 24, 2008
3
0
Everything is set to 0 at start. I understand that but I don't even know how the circuit works.

4. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Further hint - if the Q outputs are 0, what must the ^Q outputs be? What happens when you clock the flip flops based on the inputs?

5. ### DaffyD Thread Starter New Member

Sep 24, 2008
3
0
Okay, here is what I don't understand specifically. When the clock pulses, does it toggle J or K or both? Or does it toggle J on the rising edge and K on the falling edge? Thanks for your help.

6. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Have you looked at a truth table for a J-K flip flop? The state toggles based on the state of the J and K inputs. Get a data sheet for a 7472 to see how they work.

Jul 17, 2007
22,183
1,728