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74190 up/down decade counter help

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I may have completely miss understood what you were saying, but I think I wired this the way you suggested.

I'm having 2 problems now, first it counts down from 59-9-59-50-59-50-49-9
it's also decrementing the minutes on the second 59 count, it's just strange.

(I only modified the counter for tenths of seconds)
 

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chelm said:
I'm having 2 problems now, first it counts down from 59-9-59-50-59-50-49-9
it's also decrementing the minutes on the second 59 count, it's just strange.

(I only modified the counter for tenths of seconds)
I don't understand tenths of seconds. Aren't you counting seconds in the right display?

You did the clocks backwards. If you look at my circuit the high frequency goes to the load FF (U17 in your circuit) and the divide-by-2 frequency goes to the counter.

-----------------------------

I used to be fast and sloppy. But now that I'm getting older, I'm losing my speed.
 
Yes I misspoke, or mis-wrote rather. Tens of seconds is what I meant, sorry. I'll take a closer look at this, I thought I had it setup the same way you did. I apologize if I missed something.
 
So I connected it like this: I think this is what you meant, but now they count independently. The seconds count like this: 59-50-59-50-49-40-49-40-39-30-39-30-29...
 

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Sorry, I wasn't more clear.
The divide-by-2 FF clock is now your main 1 second clock and goes to all the counters. The undivided clock goes only to the carry FF's.
 
Doing the Impossible

Not impossible, just difficult. Difficult we do right away. Impossible just takes a little longer.

You could use a Quad 2-Input Mux such as the 74LS157 to set the counter values for the divide by 6 counters. The Mux SELECT input is controlled by the J7 Preset/Load switch. This allows selection of either the load switch values or the divide by 6 values for the Counter Preset. (The Mux is not needed for the counters that go to 0 and rollover to 9.)

The Mux Select input goes to J7. The Mux I0 DATA inputs go to the Counter Preset Switches and the Mux I1 data inputs go to the desired count preset value for a divide by 6. The Mux outputs go to the counter DATA inputs. In the J7 load position (Mux Select Low), the counter presets are thus connected to the switches. In the J7 run position (Select High) the presets are set to the hardwired values to cause the proper divide ratio. For example the 10's minute digit would be loaded to binary 5 on the next count after it reaches zero.

Since the counter load control is asynchronous you will need a D flip-flop to delay the counter load signal until the count following 00 for the counters you want to divide by 6. Otherwise it would instantly load 5 when it reached 00. Connect the RCO signal from the counter to the D FF input and the FF Q output to the counter LOAD input. The FF clock should be 2Hz for proper sync of the LOAD signal.

You will also need to add 2-input AND gates at the divide by 6 counter LOAD inputs. The AND inputs are the FF output and J7 so either can control the LOAD function for the divide by 6 counters.

Hope you can follow all that. I could draw if for you but what's the fun in that. As they say in the textbooks, that's left as an exercise for the reader. It's not a trivial addition to the circuit but, I think, doable.


Sir Ive done what you said but why is it when the counter reaches 09, it immeadietely comesback to 59
 
hi Mark,
Please dont keeping posting to multiple threads with the same question, it gets confusing.;)
E
 
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