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clock using 74LS393 (help)

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striker_24

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Anyone here knows how to make the schematic of "hours" in a 12-hour digital clock using 74LS393?

Coz we already hav a schematic of "hours" (12-hour clock) however, it is only functioning well in simulation,not in actual..

Kindyl take a look at this thread..

http://www.electro-tech-online.com/threads/12-hour-digital-clock-help.92727/

If anyone can help me to build a schematic of "hours" (12-hour clock),will appreciate it much..


Thanks lot!


striker_24
 

ericgibbs

Well-Known Member
Most Helpful Member
Anyone here knows how to make the schematic of "hours" in a 12-hour digital clock using 74LS393?

Coz we already hav a schematic of "hours" (12-hour clock) however, it is only functioning well in simulation,not in actual..

Kindyl take a look at this thread..

If anyone can help me to build a schematic of "hours" (12-hour clock),will appreciate it much..


Thanks lot!


striker_24
hi,
Why have you crossed linked your two threads, its annoying to keep switching back and forth.

Usually in a circuit that fails in real life versus a simulation, its due to gate propagation delays.
 

striker_24

New Member
wat do u think is the possible problem buddy?

Do u hav any idea how to solve this problem? or how to change our schematic in "hours"?

thanks lot!
 

ericgibbs

Well-Known Member
Most Helpful Member
wat do u think is the possible problem buddy?

Do u hav any idea how to solve this problem? or how to change our schematic in "hours"?

thanks lot!
hi,
Ive looked a few times.!
If you pause the video about the reset time, you are clearing the hours but the mins/secs are still showing 59:59.
After the 59:59 clears to 00:00 the hours units is set to a '1'.

I would try a an R/C delay into the hours units reset line, make it reset until the 59:59 becomes 00:00.
 

ericgibbs

Well-Known Member
Most Helpful Member
how would i do this bud?
hi,
Looked again at the video.:)

I assume you want a 12 hour clock.??

So if you count to 12:59:59 isnt the next 1 second time 01:00:00 .?

The 12 hr clocks Ive used 11:59:59 > 00:00:00 both at midday and midnight, with an 'am/pm' indicator.

Unless I'm missing something.:)
 

striker_24

New Member
ah..

however,00:00 as 12 o'clock is not valid for our project..it must be 12:00 during 12 o'clock..

anyway,thanks for ur rply bud..
 

ericgibbs

Well-Known Member
Most Helpful Member
ah..

however,00:00 as 12 o'clock is not valid for our project..it must be 12:00 during 12 o'clock..

anyway,thanks for ur rply bud..
hi,
But what I said about your display incrementing from 12:59:59 to 01:00:00 is still valid.

Thats what your clock is doing, what do you want to display after 12:59:59..?
 

mvs sarma

Well-Known Member
we expect 01-00 after an hour after, 12mid night or 12 afternoon. How ever, I wonder whether the gates U17A and U17B are really needed and have a function? even the am/pm indicator not needed as one knows whether it is day or night, unless it has calender display with day of week & date.
 
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