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

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coolkid

New Member
Still very new to this,I hope you guys will help me in this journey.I am tasked to create a 24hr clock using 74ls93 ic and im using 74ls47 bcd decoder and 7seg anode led.
Image below shows what i have done so far,and i not sure why the numbers are liddat.Please help
 

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atferrari

Well-Known Member
Liddat?
 

JimB

Super Moderator
Most Helpful Member
Does this exist in real hardware, or is it just a simulation?

I notice that you are running the clock at 1kHz, if this was real hardware your eye would see the LS digit as an 8, your eye is not fast enough to see the changes.

If this is a simulation, the simulator software will display who knows what?

I suggest that you slow the clock to 1 or 0.5 Hz and see what happens.

JimB
 

coolkid

New Member
Does this exist in real hardware, or is it just a simulation?

I notice that you are running the clock at 1kHz, if this was real hardware your eye would see the LS digit as an 8, your eye is not fast enough to see the changes.

If this is a simulation, the simulator software will display who knows what?

I suggest that you slow the clock to 1 or 0.5 Hz and see what happens.

JimB
Thks for the tip,but after slowing the clock,the result is still the same,the numbers kept "jumping".
i tried 1hz and 0.5 hz.(see the images attached)
 

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coolkid

New Member
Im trying to cascade a mod 2 and mod 12 counter to form a mod 24 counter that counts to 24 then resets to zero.(at least thats what i think im doing).
i also need to add :
Two push button (or pulse) switches .One of the pulse switch will function as the manual clock signal generator used for adjusting the start time

. The second pulse switch will be used as a toggle switch to select either the manual clock pulse or the free running clock signal.

An LED indicator is also required to light up whenever the manual (or adjust) mode is selected.
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
You have the second nand pair connected to 2 only.... To count to twelve you need to feed the output of the first nand to the input of the second... As the second nand needs to see the 2 and the 10. The first nand needs to be connected to 2 and 4 ( 10)
 
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coolkid

New Member
works fine now,thks for the help.Can i ask what the freq on the clk you used in your simulation?(your design).

You have the second nand pair connected to 2 only.... To count to twelve you need to feed the output of the first nand to the input of the second... As the second nand needs to see the 2 and the 10. The first nanad needs to be connected to 2 and 4 ( 10)
Also could you explain a bit more for this part,i want to learn,as i was amaze by how a little tweaking solved the problem.(i dint know what i was doing the whole time)

And lastly ,It'll be great too if you can recommend some ideas to implement "set time mode" using pulse switches,i have the general idea how it should work,but i just dont know where to start or what to use.

Two push button (or pulse) switches .One of the pulse switch will function as the manual clock signal generator used for adjusting the start time

. The second pulse switch will be used as a toggle switch to select either the manual clock pulse or the free running clock signal.
 

Ian Rogers

User Extraordinaire
Forum Supporter
Most Helpful Member
1) frequency was 2hz ( just for testing )

2) Your nand gate reset at 12.... decimal doesn't go to 12 only 9.. Set the reset at 10 and the thing counts up to nine and resets. The second has to look at 2 on the second register and 4 on the first... Then it resets when the total count hits 24..

To set the time you will need to clock each manually .. Set a debounced switch... Ored with the clock input... When the switch is pressed the hours increment..
 

coolkid

New Member
Im pretty sure i am wrong on this one,i am trying to make use of two pulse switches(push switches),the first acting as the mode selection(between "free run" and "adjustment" mode),and the second acting as a manual clocking.(see attached image).I need the switches to latch,like a on-off switch,i found out that i need jk ff in order to do so.Also i want to add a led that will light when "adjustment" mode is on.
Help and tips will be appreciated.
 

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coolkid

New Member
You still need an or gate... The clock is an output and so is the JK flipflop...( erm! Smell something!!)

Most use the "Adjust Mode" button as a through switch If it isn't pressed nothing happens.
These are the changes that i have made,the led still doesn't seems to work.However the switches are okay now,and im able to choose between 'free run' and 'adjust' mode just fine.
However the numbers sometimes are laggy and jerks a lot,is there something still wrong? also could you explain more about the Adjust Mode" button being a through switch?
 

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Nicolas de PAOLI

New Member
Still very new to this,I hope you guys will help me in this journey.I am tasked to create a 24hr clock using 74ls93 ic and im using 74ls47 bcd decoder and 7seg anode led.
Image below shows what i have done so far,and i not sure why the numbers are liddat.Please help
Hello !

Voici ma création, une horloge réveil multiplexée à base de 33 TTL IC.

Translation: Here is my creation, a multiplexed clock based on 33 TTL ICs


<Mod note: ETO is an English-speaking site. If you want to post, please first translate it to English. Thank you.>
 
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