1 to 6 counter using 74191

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12
as a school project i am required to make a 1 to 6 counter using 74191 meanwhile i cant really get how it works. After searching and using trial and error method i was able to make it count from 1 to 7 by entering the input 0001 and connection only the first 3 least significant bits of the output
i followed an online tutorial on how to make it count from 0 to 15 and all the other changes are the result of trial and error.
i also read 74191's data sheet but still didnt understand how it works 1 to 7.png
 

djsfantasi

Joined Apr 11, 2010
6,145
Welcome to AAC!

When your counter reaches 6, what happens next?

If you still don't understand how it works, something must be confusing you. What is it about the 74191 that you still find confusing?
 

dl324

Joined Mar 30, 2015
10,003
Welcome to AAC!

What have you been studying? In particular, what have you studied about 74191?

You have the preset set to 1. What could you do to make the counter load 1 and not display 7?

What is it that you don't understand in the datasheet?

EDIT: With respect to the other suggestions you've been given. This is how load works on 74191:
1572113785321.png
 
Last edited:

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12
Welcome to AAC!

What have you been studying? In particular, what have you studied about 74191?

You have the preset set to 1. What could you do to make the counter load 1 and not display 7?

What is it that you don't understand in the datasheet?

EDIT: With respect to the other suggestions you've been given. This is how load works on 74191:
View attachment 189770
after searching again i found someone that made a combination circuit that would only input 1 to load at required values but when i did so but it again didn't work1 to 7 2 .png
 

dl324

Joined Mar 30, 2015
10,003
after searching again i found someone that made a combination circuit that would only input 1 to load at required values but when i did so but it again didn't work
I haven't worked through the decode logic (yet). What did the circuit do?
 
Last edited:

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12

dl324

Joined Mar 30, 2015
10,003
so i did my truth table and came up with the equation
Please label the columns in the truth table and Kmap. You seem to be using A as the most significant bit; which is backwards from the datasheet. If that's the case, I only agree with one of your minterms.

What you should be trying to do is to get the counter to go to 1 after it counts up to 6. Your original attempt was almost correct except that it counted to 7 before starting at 1 again.
 

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12
Please label the columns in the truth table and Kmap. You seem to be using A as the most significant bit; which is backwards from the datasheet. If that's the case, I only agree with one of your minterms.

What you should be trying to do is to get the counter to go to 1 after it counts up to 6. Your original attempt was almost correct except that it counted to 7 before starting at 1 again.
Q3=A (most significant)
Q2=B
Q1=C
Q0=D (least significant)
i am sure of this because i tried connecting them with load always high and it did count from 0 to F in hexa
as about my truth table i used an online generator to make sure that i don't create a wrong equation and that was the answertt.png
 

dl324

Joined Mar 30, 2015
10,003
as about my truth table i used an online generator to make sure that i don't create a wrong equation and that was the answer
OK, I missed a negation on the 3rd term. But this is still the wrong way to go.

The counter is synchronous with an asynchronous load. So you should be able to use a simple circuit to decode a certain count to be used to load 1 into the counter.

The circuit is more complicated if you want to guarantee that a count of 0, 7-15 is never displayed.
 

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12
Please label the columns in the truth table and Kmap. You seem to be using A as the most significant bit; which is backwards from the datasheet. If that's the case, I only agree with one of your minterms.

What you should be trying to do is to get the counter to go to 1 after it counts up to 6. Your original attempt was almost correct except that it counted to 7 before starting at 1 again.
ok it tried something else
i used the output of the normal 0 to 15 counter as my binary input source and the results will be the output of the combination circuit11234566...pngWhatsApp Image 2019-10-26 at 10.22.10 PM.jpeg
although the output now is 11234566.. i am very happy with my product
thank you so much for ur effort
 

dl324

Joined Mar 30, 2015
10,003
although the output now is 11234566.. i am very happy with my product
But this circuit doesn't do what you were supposed to do.

Go back to your original circuit (and connect all 4 outputs from the counter to the display). If you do that, you'll find that the counter is counting past 7.

You need to find a way to have the counter reset after counting up to 6.
 

Thread Starter

zeinatamer1232

Joined Oct 26, 2019
12
But this circuit doesn't do what you were supposed to do.

Go back to your original circuit (and connect all 4 outputs from the counter to the display). If you do that, you'll find that the counter is counting past 7.

You need to find a way to have the counter reset after counting up to 6.
i really cant think of any other solution
i tried everything that came to my mind before posting the question here.
been working on the logic of this circuit for 3 days
i am out of ideas
 

absf

Joined Dec 29, 2010
1,942
Using CMOS 4027 also works.

There is still one more problem for you to slove. When starting up, you'll see that it always starts with zero. Can you also make it a "1" when switched on?

Allen
 
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