MOD-60 counter with stop/start and reset buttons

Thread Starter

XxdeadshotxX

Joined Nov 8, 2019
28
You had a circuit working with LS93. Converting that circuit to use D flip flops should be straightforward if you read the LS93 datasheet.
what my lecturer want is to keep my LS93 counters. He just task us to add start stop buttons to the circuit using a 74LS74
 

djsfantasi

Joined Apr 11, 2010
9,156
Just curious? What have you done or tried as far as using the D flip flop for your start/ stop sub circuit? It’s been over two days since your post, and I haven’t seen anything with regard to your efforts. You realize that no one here should tell you how it’s done? This is Homework Help (not Done!) after all.

Think about what you need. You must ‘toggle’between stop/start. Which is what a flip does...
 

djsfantasi

Joined Apr 11, 2010
9,156
Could you post the complete text of the problem? I think it would be easier to use logic gates instead of flip flops.
But the TS has stated that he completed the problem with logic gates and it was rejected by the instructor. Subsequently, the instructor added that the start/ stop feature must be implemented with a 74LS74 flip flop.
 

dl324

Joined Mar 30, 2015
16,839
Hi i have done a design with it but i encounter some problem with my reset button. It only resets to the nearest 10th like 10 or 20 when i press it instead of 0. pls advice
It would be helpful if you stopped taking pictures of your screen and either posted screen captures or clips from printed output. They'd be easier to read and wouldn't have moire patterns at certain magnifications.

It would also help if you stopped putting unnecessary crossings and jogs in the wires. You can use the shift key while routing to make Multisim use more direct routing and you can always move the wires after routing.

I don't even want to try to read your messy schematic.
mod60clip.jpg

This is what I meant when I said using logic gates to implement start/stop and pause.

Where is the LS74 that you're required to use?
 
Last edited:

djsfantasi

Joined Apr 11, 2010
9,156
So, here is a hint. The two gates U5A and U6A form the equivalent of an 74LS74!

Make sure you understand what U5A and U6A are doing. Then, check out the 74LS74 datasheet, either the General Description or the Functional Table.
 

djsfantasi

Joined Apr 11, 2010
9,156
More hints. You’re picture shows J1 and J2... Do you know what pull up or pull down resistors are? You can use simpler switches. And for this, since your clock is slow, you can get away w/o debounce.
 

djsfantasi

Joined Apr 11, 2010
9,156
Hi i tried to use pull up resistor but the problem still persist.
What problem? I thought you had a working circuit and just had to replace the gate logic with a 74LS74?
Forget the pull ups for now. It should be easier later, once you have the start/stop circuit working with a D type flip flop. It probably isn’t needed for your assignment.
 

Thread Starter

XxdeadshotxX

Joined Nov 8, 2019
28
What problem? I thought you had a working circuit and just had to replace the gate logic with a 74LS74?
Forget the pull ups for now. It should be easier later, once you have the start/stop circuit working with a D type flip flop. It probably isn’t needed for your assignment.
Now my circuit is working but its not working correctly. My reset button only resets it to the nearest 10th instead of 0.
 

Thread Starter

XxdeadshotxX

Joined Nov 8, 2019
28
What problem? I thought you had a working circuit and just had to replace the gate logic with a 74LS74?
Forget the pull ups for now. It should be easier later, once you have the start/stop circuit working with a D type flip flop. It probably isn’t needed for your assignment.
Now my circuit is working but its not working correctly. My reset button only resets it to the nearest 10th instead of 0.
Do you understand why only the least significant digit is being reset?
NO! IM SORRY:( i just took this module this sem and i don't understand much
 
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