Problem encountered on building a 24 hr digital clock,only hours portion.Help needed

Thread Starter

Jesse de lala

Joined Oct 15, 2023
MOD NOTE: Split from this thread.

@Jesse de lala : Please don't hijack another member's thread. You now have your own.

Hello guys! I'm having problems in my study homework. I'm trying to make a counter with JK's flip-flop, but, I'm having such a big problem with the logic in the hour. (make the counter go until 23 hours). Please, if someone can help me this.
I'm not using CI, only flip-flops and gates.
Here is my circuit in NI MULTISIM simulator. circuito completo.png
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Joined Mar 31, 2012
What is the specific problem that you are having? Describe exactly what it is doing that it shouldn't, or not doing that it should.

What steps have you taken to diagnose and/or fix the problem and what have those efforts revealed?


Joined Mar 30, 2015
Welcome to AAC!
I'm having problems in my study homework.
Please post the entire text of the problem so we can see what you're being asked to do.

I take it that you haven't learned how to design counters without needing to use the set/clear inputs on the flip flops.

EDIT: cropped schematic
It looks like you copied the 0-59 counter for hours and never modified it to be 0-23.
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Joined Mar 30, 2015
It turns out that I had already designed something like this:
In my case, I designed synchronous mod9 and mod3 counters instead of using ripple counters. I used clear on the flip flops instead of designing a mod24 counter which would have required a 5 bit binary to BCD converter to display hours.

Do you notice how much easier it is to read this schematic style?

EDIT: Here's a synchronous mod24 counter. It required the addition of 4 AND gates and the binary to BCD conversion:
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