Digital Clock using 74LS192

Thread Starter

alvinteoo

Joined Dec 21, 2019
9
Hi people

I would like to make a digital clock with HOURS and MINS using 74LS192 IC. Below attached is my schematic diagram for the connection of the circuit. However, the MINS counter keeps counting from 00-59 and resets and does not increase the HOURS counter after each 60mins.

Components:
74LS192 IC
74HC00 IC
555 Astable timer
Capacitor
Resistors

Please advise me on this. Thank you! :)
 

Attachments

ericgibbs

Joined Jan 29, 2010
9,563
hi a.
Welcome to AAC.
IC2 /TC will not happen, because you are resetting/reloading IC2 with the '6' count.
Try using the '6' out to step the hours.
E
 

djsfantasi

Joined Apr 11, 2010
6,175
Thank you, alvinteoo!

As this is homework, we shouldn’t provide a direct answer but lead you to find the correct solution yourself.

The previous comment was basically asking you how you are counting the minutes? What signal are you using to increment minutes?

And then answer why you believe this is the correct signal. Don’t worry about your answer. A simple direct answer is best.
 

ericgibbs

Joined Jan 29, 2010
9,563
hi,
You do not disconnect the NAND pin 3 from IC2 Pld, you connect pin 3 of the NAND gate to the Cp of IC3.
All the Pin Para inputs should be connected to 0v

Draw a sketch of these modifications and post it.

E
 

dl324

Joined Mar 30, 2015
10,067
when connect pin #3 to Tcu of hours it will cause the min to be a full 00-99 counter.
Why do you have all of the clear pins connected? The 10 minute digit needs to reset independently. Since this is a decade counter, the least significant minutes digit doesn't need to be cleared.

Is this supposed to be a 12 hour clock? Or 24? How are you going to calibrate the 555 timer?
 

dl324

Joined Mar 30, 2015
10,067
This is what I transcribed from your schematic:
clipimage.jpg

Note the decoding on the hours counters.

Also note that the 74LS192 isn't guaranteed to satisfy the HIGH level input voltage for 74HC4511.
clipimage.jpg
clipimage.jpg

You're okay with typical parts but, if you get an outlier, it won't work. The proper way to drive HC from LS is to use a pull up resistor.
 
Top