I am currently doing a school project with the theme kids game. I am using NE555 timer, 74LS192 and 74LS47 to build a down counter counting from 99-00 to limit the players' time but how can I stop the counter at 00 instead of looping back to 99?

 

hi JO,
Please post the circuit you have so far, then we can help with modifications.

You say a school project, is this school Homework.?

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How do you count? What’s the 555 for and where does it connect?

To answer your question, stop counting.

What pin on the 74ls192 tells you when you have hit 0? What pin does that and let you daisy chain counters?

Since this is a school project, it belongs in Homework Help. As such, we can’t give you the answer but guide your solution.

You should post your current schematic (hand drawn neatly is ok).

 

I do not believe that a school project automatically means homework. As always- need more information.
All counting outputs to a big AND gate, output to 555 pin 4, reset ??
Might it be possible that borrow output provides the big AND function?

 

Post your circuit diagram, the 74LS192 pin 14 is reset..

 

Might it be possible that borrow output provides the big AND function?

As can be seen in the attached diagram, the BORROW output does indeed provide an indication that the down count for that digit has reached zero. However, the down count clock also controls the BORROW output, so you would need to account for that fact if you use the BORROW signal to control the clock source in your design.

 

The answer have been deleted.

Please don't provides the direct answer or close to the answer, provides the direct answer won't help the student and also may cause you get ban from Homework Help forum.

Thanks for your cooperation.

 

Until we know whether this is homework, we shouldn't be telling the OP how to do it.

EDIT: Just noticed that the thread has been moved to Homework Help. We need to let the OP do most of the work.

 

Thank you to the hints given. I am new to the website previously and didn't realize there's a Homework Help forum exists.
Not sure whether is this the hint you trying to provide me but the circuit working well.

 

The way to stop a counter is to AND the CLK signal with a STOP signal.
It appears that this is what you have done in your schematic diagram.

You could have avoided all the "glue" logic by taking advantage of the RCO output of the most significant counter.