That’s a good observation!

However, for the second digit of the seconds and minutes, when do you need a reset?

 

That’s a good observation!

However, for the second digit of the seconds and minutes, when do you need a reset?

Umm for the tens? Or the units?
If for the units, the moment they reach 9 they need to send a signal to the tens, and if for the tens, they need to send a signal the moment they reach 5. Which is another problem... maybe with AND gate for each of them individually?

 

Umm for the tens? Or the units?
If for the units, the moment they reach 9 they need to send a signal to the tens, and if for the tens, they need to send a signal the moment they reach 5. Which is another problem... maybe with AND gate for each of them individually?

Is the second digit of minutes (or seconds), the tens or units?

And consider whether or not an AND gate is required.

 

Is the second digit of minutes (or seconds), the tens or units?

And consider whether or not an AND gate is required.

From left to right which we read the clock... means the units. The AND gate is not required there, we can connect Qd to A clock of 7492 and send the signal through there. And use the AND gate for the tens numbers. Please correct me if i'm making mistake

 

for the tens we're using 7492 because it has a 12 mod and a 6 mod

But look at how the schematic you found has the 10's second counter wired. They have the clock from the 1's second counter going to the A clock and it should be going to the B clock. They have the B clock coming from QA and that implements divide by 12 functionality.

 

Hello,

Have a look at the databooks for selecting the chips.

Bertus

 

Also look at the count sequence for the divide by 6:

It's 0, 1, 2, 4, 5, 6. That's okay for a divide by 6, but not for the 10's second counter. It needs to count in the normal order.

 

Also look at the count sequence for the divide by 6:
View attachment 256209
It's 0, 1, 2, 4, 5, 6. That's okay for a divide by 6, but not for the 10's second counter. It needs to count in the normal order.

Ok now wit this table i'm getting a bit confused... can you open it a little bit more?

 

Ok now wit this table i'm getting a bit confused... can you open it a little bit more?

When you use 7492 as a divide by 6, you only use the B, C, and D flip flops and feed the clock to the CLKB input. If you look at the table, and ignore the A output, you can see the count sequence isn't what you need.

Could you post a link to where you found that schematic? I'd like to see why they claim it's a 24 hour clock.

 

When you use 7492 as a divide by 6, you only use the B, C, and D flip flops and feed the clock to the CLKB input. If you look at the table, and ignore the A output, you can see the count sequence isn't what you need.

That makes sense... now i think i'm understanding

 

That makes sense... now i think i'm understanding

What is the name of this class, school, and teacher?

I find it unusual that a teacher wouldn't give better instructions, but not so unusual for a student to miss some important information because they didn't realize it was important or weren't paying attention. Is this college level?

 

What is the name of this class, school, and teacher?

I find it unusual that a teacher wouldn't give better instructions, but not so unusual for a student to miss some important information because they didn't realize it was important or weren't paying attention. Is this college level?

Unfortunately yes, college level, they didn't give us any kind of instructions, and i'm living in middle east unfortunately... so... there's nothing i can do with their names i guess.

 

college level

Still, it's unusual for a student to be given an assignment where they don't even know where to start.

We can give guidance, but it's helpful for us to know what the constraints are so we don't head you down the wrong path. I don't remember learning to use commercial counters in college, but it was a long time ago.

 

Still, it's unusual for a student to be given an assignment where they don't even know where to start.

We can give guidance, but it's helpful for us to know what the constraints are so we don't head you down the wrong path. I don't remember learning to use commercial counters in college, but it was a long time ago.

I really appreciate any help i can get, it's a group project, and most of my classmates are not even fluent in english like me to ask question around.
I am allowed to use 7492, 7490, seven segments common anode, 7447, 7432, 7408, 7400 for the logical gates and 555 (already made the astable circuit and working exactly as it should, so... that does count for something maybe?). I do have 7493 too, but we're not allowed to use that. I don't have 7490 right now, and have to order it. I do have 2 7492 which are not enough. And I also have to order 4 more 7447. Right now i'm not exactly sure if i must order 1 more 7442 and 3 7492 or not, i'm sure i must order 4 7447 tho... so, there are many problems. I also can use a top switch to make a reset button for the whole circuit, alse this is being made on bread boards. I have 3 of them.

 

I am allowed to use 7492, 7490

You can use all 7490, all 7492, or a combination. There's an advantage for using 7490 for the second and minute counters (do you know why), but all of the other counters will require logic to reset them at appropriate counts.

Is there a reason why you're being told to use standard TTL? CMOS is less expensive these days and uses less power.

 

You can use all 7490, all 7492, or a combination. There's an advantage for using 7490 for the second and minute counters (do you know why), but all of the other counters will require logic to reset them at appropriate counts.

Is there a reason why you're being told to use standard TTL? CMOS is less expensive these days and uses less power.

Unfortunately I must do a combination. What's the advantage of using 7490 for minute and second counter?
Professor didn't give any reason, i originally had plan to do it with 4033 myself, which he said I can only use these components.

 

What's the advantage of using 7490 for minute and second counter?

The minutes and seconds each require a modulo 6 and a modulo 10 counter. What types of counters are 7490 and 7492?

i originally had plan to do it with 4033

Since CD4033 have outputs for seven segment displays, decoding a specific count can be more involved than decoding from binary outputs.

 

@arian78

You can use all 7490, all 7492

Actually you can't use all 7492. Can you explain why?

 

@arian78
Actually you can't use all 7492. Can you explain why?

Because it doesn't have a mod 10 counter? And if it doesn't have, which counter does have?
While 7490 has only a mod 6 counter which makes it perfect for tens of minutes and seconds, but we can't use it for hours units at all?

 

While 7490 has only a mod 6 counter which makes it perfect for tens of minutes and seconds, but we can't use it for hours units at all?

Hi arian,
This is the logic digram for 7490, why do you think it is not suitable.?

Which type of decade counter IC's do you have on your work bench.?

I would suggest you build just the Seconds , Tens and Units ,with their LED displays, drive the dividers with your 555.

This will prove the first section of the counter '00' through '59' seconds.

E