Synchronous counter 00-99 using 74192, 7447, and 7 segment display

Thread Starter

DW10

Joined May 2, 2018
6
Hi,
I'm working on a project to build a synchronous counter that counts up 00-99 and starts over using 74192 BCD decade counter, 7447 BCD to 7 segment and 7 segment ics. It is also supposed to have an asynchronous reset using a momentary switch. I have only used JK flip flops to build counters before so I am pretty lost right now.
 

Thread Starter

DW10

Joined May 2, 2018
6
Yes it is, it is one part of a project. The 74192 is throwing me off, I have been researching it but still don't quite understand how it works.
 

dl324

Joined Mar 30, 2015
11,822
Yes it is, it is one part of a project.
For homework, we're only allowed to offer guidance. Students are expected to do most of the work.
The 74192 is throwing me off, I have been researching it but still don't quite understand how it works.
If you're trying to implement a BCD counter, why are you using 74192?
Ignore that, 74192 is BCD.

Have you read the datasheet? What don't you understand?
 
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Thread Starter

DW10

Joined May 2, 2018
6
It is the ic I am provided with. I have gone over the datasheet, but it's not like anything I have used before. I was only introduced to counters last week and was just getting the hang of JK flip flops. The most trouble I am having is connecting the pins between the ics. I have been working on a paper schematic because I understand it better on paper
 

dl324

Joined Mar 30, 2015
11,822
The most trouble I am having is connecting the pins between the ics. I have been working on a paper schematic because I understand it better on paper
Post a picture of your schematic and tell us what you don't understand.
 

Thread Starter

DW10

Joined May 2, 2018
6
This is how far I've gotten. I feel like I'm missing pins on the 74192. I only need a count up which is supposed to come from a function generator.
 

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absf

Joined Dec 29, 2010
1,948
This is how far I've gotten. I feel like I'm missing pins on the 74192. I only need a count up which is supposed to come from a function generator.
7447 pins 3,4 & 5 should be tied high; and 74192 pins 15,1,10 & 9 should be tied low if you're not using them as preset inputs.

As you're counting up, send the clock pulses to pin 5 and make pin 4 high (of the upper 74192)

Allen
 

dl324

Joined Mar 30, 2015
11,822
Thank you for posting an easy-to-read schematic. A couple suggestions: be consistent in your usage of connection dots, and try to avoid unnecessary wire jogs. A good job overall.

I find that when drawing clock/timer circuits, it's convenient to not follow the guidelines for signal flow (left to right and top to bottom) so they're "right" reading. This is an example, most significant digit on the left:
counter.jpg
I feel like I'm missing pins on the 74192.
What do you think is missing?

Everything you need to know about 74192 and 7447 should be in the datasheets. Because this is homework, you should try to glean relevant details from them.

Post questions if there are things that you're not finding and we can point you to the relevant section(s). If you do have questions, it would be helpful if you posted the datasheets you're referencing or the IC manufacturer (though operation should be the same for all manufacturers; that's the whole point of second sourcing).

Regarding the current limiting resistor value you should use; that's determined by the desired current in the displays and, since you aren't using external drive circuitry, the output drive capability of the of the decoder.
 
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dl324

Joined Mar 30, 2015
11,822
Should there be inputs for A-D on the 74192? I'm not sure what it would be if there is.
Since you've disabled the preset inputs by connecting LOAD# to VCC, you can leave them floating. Floating inputs don't cause increased power dissipation in bipolar devices, unlike CMOS.
 
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