Building a Digital Clock ..#2

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Raj@1963

Joined Feb 19, 2021
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MisterBill2

Joined Jan 23, 2018
9,475
You need more bits in the binary counter section, five should be adequate, in theory 5 bits allows a count from zero to to 31. Then you also need to detect counts of 14 and 25 to reset to zero. And beware that some 7400 series logic is "low-true"
 

dl324

Joined Mar 30, 2015
13,293
Welcome to AAC!

You can't operate 74xx TTL at 6V.

I'll take a closer look at your mod 12 counter attempt and get back to you...

EDIT: Are you opposed to using a flip flop to keep track of how many times the 'ungated C' output toggles? That's what I think they intended to be used for implementing divide by 12.
 
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dl324

Joined Mar 30, 2015
13,293
I don't see how you can implement a 12 hour clock. You need to be able to preset the hours display to 01 when you start and when it rolls over from 12:59 and CD4026 only supports reset to 0.

This is how I decoded 13:
clipimage.jpg

A 24 hour clock makes more sense because you can have hours count from 00 to 23.
clipimage.jpg
The OR gate is to allow the counter to be reset manually. The simulator I'm using starts the counters at 10.
 
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