counter which increment by +3

AnnaJK

Joined Jun 11, 2017
3
I'm struggling with making digital circuit counter,

which is has to be a counter(or anything that can be work with clock signal) that starts from 0 to 90 (in decimal number)
and it has to be addend by 3. (ex. 0, 3, 6 , ... 90)

I was trying to make a circuit like this, (plz look at the image I uploaded)

I connected 74_190 counter with a a 74_283 adder, so when it counts up with 1, adder could add with 2 so finally i can get add 3.

but sadly when I run it, it just adds up with +1.

How can I figure this out? I tried to slove this problem for 3 days but did not... Pleas help!

#1

DickCappels

Joined Aug 21, 2008
9,318
In your breadboard I hope you used plenty of power supply bypass capcitors to minmize false triggering of your edge sensitive devices.

There are probably many good ways to do this. Basically, you want to have count be three times the number of input pulses. How can you generate a count that is three times the number of input pulses? Would clocking more than one counter at a time be of any use to you?

There are some less parts intensive approaches using things like XOR gates, resistors and capacitors to generate delays. Not as flexible as a logic-only approach.

AnnaJK

Joined Jun 11, 2017
3
Thanks. I changed my circuit like this, but it adds +1 (0, 1, 2, ...)
Why does that adder not working?

djsfantasi

Joined Apr 11, 2010
8,574
Perhaps your algorithm might be wrong?

If you increment a counter and then add +2 to it, what is the sequence of numbers that is produced?

I suggest that you make a table of the counter values with the corresponding values equal to input value + 2.

dl324

Joined Mar 30, 2015
15,115
Welcome to AAC!
I'm struggling with making digital circuit counter, which is has to be a counter(or anything that can be work with clock signal) that starts from 0 to 90 (in decimal number) and it has to be addend by 3. (ex. 0, 3, 6 , ... 90)
Are you sure you're supposed to implement the circuit by adding 3 to the output of the first counter? If you do that, carry out from the first counter won't increment the second counter correctly.

Are you required to use the '190 counter?

Could you post the complete text of the problem?

Last edited:

AnnaJK

Joined Jun 11, 2017
3

Actually I'm making a digital clock in other planet that counts +3 each second, from 0 to 90. So it could be 0, 3, 6, ... , 87, 0(90), 3, 6, ... (repeat)

So I tried to make it like the upper image but I suddenly found that there was a problem. (like it just adds only at the first time, like 0, (1+2=)3, (2+2=)4, (2+3=)5, ...)

p.s. There is no restriction that has to use 190 counter. It is free to use anything.

Is there anything that I can figure this out with?

Thanks,

dl324

Joined Mar 30, 2015
15,115
Is there anything that I can figure this out with?
Could you post the complete problem description?

What has your class studied prior to this assignment?

djsfantasi

Joined Apr 11, 2010
8,574

Actually I'm making a digital clock in other planet that counts +3 each second, from 0 to 90. So it could be 0, 3, 6, ... , 87, 0(90), 3, 6, ... (repeat)

So I tried to make it like the upper image but I suddenly found that there was a problem. (like it just adds only at the first time, like 0, (1+2=)3, (2+2=)4, (2+3=)5, ...)

p.s. There is no restriction that has to use 190 counter. It is free to use anything.

Is there anything that I can figure this out with?

Thanks,
So you figured out the problem with your method. Good.

You can use the components that you have with one exception. More on that later.

You want this sequence;
0,3,6,...,87 from this sequence:
0,1,2,...,29

The new sequence can be expressed with what equation? Hint, it is a linear sequence...

Once you have the equation, how can you implement it with 74_283s?

The exceptions I don't see yet are existent in your original solution - how do you stop? And the other is going to be how do you carry? Both are simple once you discover the base algorithm.