# How to draw this logic circuit?

Thread Starter

#### Deleted member 798024

Joined Dec 31, 1969
0

Hello. This is JK flip-flop. I have to convert it into D flip-flop, that it does the same what JK does. Then I have to draw a logic circuit of D flip-flop. I don't know what to do, can you help me?

#### crutschow

Joined Mar 14, 2008
28,474
Do you know the logic sequence (timing diagram) for the JK and D flip-flops?
If not, you need to you learn them.

Then you generate the logic sequence of the circuit.

After that you will be able to determine how to convert the circuit from JK to D flip-flops (it may require some added gates).

Thread Starter

#### Deleted member 798024

Joined Dec 31, 1969
0

We drew something with friends. Do you think this is good answer of logic circuit of D flip flop?

#### MrChips

Joined Oct 2, 2009
24,982
No. How would you know that your solution is correct?

Begin by drawing the logic sequence of the first circuit.

#### crutschow

Joined Mar 14, 2008
28,474
It's not good design to just substitute the D equivalent of the JK into your circuit, as that likely is not the best or lowest part count design.
Don't be lazy.
You need to do as I suggested and look at the actual function of the circuit.
It's not that complicated.

Thread Starter

#### Deleted member 798024

Joined Dec 31, 1969
0

So with your help we got this one.

#### Delta Prime

Joined Nov 15, 2019
1,213
?

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Thread Starter

#### Deleted member 798024

Joined Dec 31, 1969
0

Maybe something like this one.

#### crutschow

Joined Mar 14, 2008
28,474
So with your help we got this one.
Maybe something like this one.
Neither of those is a good solution to the problem of replacing the JK flip-flops with D types.
Have you tried doing what I suggested?

#### MrChips

Joined Oct 2, 2009
24,982
A J-K flip-flop has four possible input states of J and K.
How does a J-K flip-flop behave for each one of these four states?
What is the behaviour when J = K = 1?

#### crutschow

Joined Mar 14, 2008
28,474
If you do not understand how to do the logic states of the devices and the circuit, or draw a timing diagram, we can help you with that.
Otherwise you are mostly just spinning your wheels.

Thread Starter

#### Deleted member 798024

Joined Dec 31, 1969
0
Thank you so much for help. To be honest I don't know how to do it. We need this homework to pass exam, but online lessons aren't so good so we try to find something in the net. We just draw something expecting it might be ok. Maybe you can help us or draw the begining of the exercise and we will see and draw the rest.

#### crutschow

Joined Mar 14, 2008
28,474
We know you don't know how to do it. That's what we are tying to help.
To start, do you know how a JK flip-flop works, and what the first circuit does, what the output (top Q) is for each clock cycle when I is high and when I is low?
Once you can explain that, then we can continue.

#### Delta Prime

Joined Nov 15, 2019
1,213
You're killing me. I only responded because It didn't look like homework until you cascaded or tied together the modified JK flip flop to D flip flop incorrectly .I'm not permitted to correct your mistake .

#### MrChips

Joined Oct 2, 2009
24,982
Thank you so much for help. To be honest I don't know how to do it. We need this homework to pass exam, but online lessons aren't so good so we try to find something in the net. We just draw something expecting it might be ok. Maybe you can help us or draw the begining of the exercise and we will see and draw the rest.
You begin by describing the 4 modes of a J-K flip-flop like I asked you to do.
Then your focus on one of the 4 modes as drawn in your exercise.
Then you describe the state of your two flip-flops after each CLOCK pulse.

Those are your first three steps before we can tackle the question itself.

#### crutschow

Joined Mar 14, 2008
28,474
You seem to want to do the design change without understanding what the circuit does.
If you don't want to understand and learn, then why are you going to school?
It certainly won't help you on any job you get.