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  #1  
Old 01-21-2010, 05:47 PM
luckyveloso luckyveloso is offline
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Default need help in 12 hour format digital clock

badly need help in analyzing or implementing the circuit diagram of the hour part in 12 hour format clock using 74ls192 or 74ls90...tnx
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Old 01-21-2010, 06:08 PM
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Hello,

Take a look at the block diagram in this thread:
http://forum.allaboutcircuits.com/sh...ad.php?t=16859

Greetings,
Bertus
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Old 01-21-2010, 06:57 PM
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How are you counting the seconds and minutes?
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Old 01-22-2010, 01:56 AM
luckyveloso luckyveloso is offline
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the seconds and minute part goes well, it counts from 0 - 59...the only problem is the hour, coz it dont start at 01...instead it start from 00 then ended at 12, then back to 00...
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Old 01-22-2010, 02:02 AM
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Use the parallel load function on the '192.
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Old 01-22-2010, 02:18 AM
luckyveloso luckyveloso is offline
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can you explain the concept of the parallel load??? i gladly appreciate it...
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Old 01-22-2010, 12:08 PM
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It's all on the data sheet. Every logic IC has one. It explains all the dunctions and how to make use of them. Google using "74ls192" as the search term.
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Old 01-22-2010, 12:09 PM
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Basically you can force the chip to start at the number of your choice.
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Old 01-22-2010, 12:55 PM
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With the 192 you could tie P0 high and P1-P3 low on the 1's place hour counter and tie P0-P4 low on the 10's place hour counter. Then you could use some decoding to take the PL inputs low during the next low to high clock transition on the 1's place hour counter.
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Old 01-24-2010, 07:16 AM
luckyveloso luckyveloso is offline
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Quote:
Originally Posted by sgardner025 View Post
With the 192 you could tie P0 high and P1-P3 low on the 1's place hour counter and tie P0-P4 low on the 10's place hour counter. Then you could use some decoding to take the PL inputs low during the next low to high clock transition on the 1's place hour counter.

can you you show me the diagram or how you decode the PL inputs? i've been working this one for already a one week now and still i couldn't figure it out...pleaseee...thanks...
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