[SOLVED] Counter IC does not count

MrChips

Joined Oct 2, 2009
30,720
Let us take a step back and understand digital ICs in more detail.

CD4026 counter/display is not necessarily the right chip for your requirements. If you want a simple multi-digit counter/display solution then this is appropriate. COUT on pin-5 is used to connect to the next CD4026 CLK on pin-1. This allows you to cascade as many digits as you wish.

If you wish to stop counting on a specific value then this is not the most convenient chip to use. Better choices would be to use a BCD (binary coded decimal) counter or even a CD4017 0-9 Johnson counter. Granted, you will need a separate BCD-to-7-segment decoder driver IC to drive the 7-segment display.

However, all is not lost. You can still use the existing CD4026 circuit. Here are some simple solutions.

(1) Use the COUT output to determine when 10 counts have been acquired. The rising transition of COUT can be used to clock a flip-flop. The output of the flip-flop is used to enable a buzzer.

(2) Add a 4017 0-9 counter that runs in parallel with the 4026. RESET both counter ICs from the same RESET button. CLOCK both counters at the same time from the same CLK signal. Now you can select any 0-9 output of the 4017 IC to enable the buzzer. It even has a 10 output but the 4026 already has this feature which is covered in option (1) above.
 

MrChips

Joined Oct 2, 2009
30,720
oh no:<<. I did not know this:(( as I've mentioned this was barely taught to us:((. Thanks a lot for this info:>. Also, I only have 7408 gate:<<
There are a lot of things that are omitted in lectures. You cannot rely on lectures to tell you everything you really ought to know.

Edit: Here is a short list (that comes to mind) of a very long list of things you need to know (that they do not teach in school).

1. Do not mix 7400 series ICs with 4000 series ICs.
2. 7400 series work on 5V power. 4000 series work with 3-18V supply.
3. Do not leave any input pin not connected.
4. Put a 10μF capacitor across the power rail (across Vcc and GND, or VDD and VSS).
5. For a production PCB, put 0.1μF capacitors across the power rail at every IC.
6. Do not drive an LED and use the same output pin somewhere else in the circuit at the same time.
7. Analog comparator (e.g. LM2903) output pins are usually open-collector. They cannot supply current on their own. They need an external pull-up resistor.
8. To pull-up or pull-down any input or output pin you need to calculate the value of the resistor given the data in the datasheet.
 

Thread Starter

gelzky

Joined Dec 7, 2021
86
There are a lot of things that are omitted in lectures. You cannot rely on lectures to tell you everything you really ought to know.

Edit: Here is a short list (that comes to mind) of a very long list of things you need to know (that they do not teach in school).

1. Do not mix 7400 series ICs with 4000 series ICs.
2. 7400 series work on 5V power. 4000 series work with 3-18V supply.
3. Do not leave any input pin not connected.
4. Put a 10μF capacitor across the power rail (across Vcc and GND, or VDD and VSS).
5. For a production PCB, put 0.1μF capacitors across the power rail at every IC.
6. Do not drive an LED and use the same output pin somewhere else in the circuit at the same time.
7. Analog comparator (e.g. LM2903) output pins are usually open-collector. They cannot supply current on their own. They need an external pull-up resistor.
8. To pull-up or pull-down any input or output pin you need to calculate the value of the resistor given the data in the datasheet.
Thank you sir for helping me out and providing me these important information:>. These are noted:> . I'm really having a hard time on this :( but I am learning thanks to everyone replying in this forum:)
 

djsfantasi

Joined Apr 11, 2010
9,156
oh no:<<. I did not know this:(( as I've mentioned this was barely taught to us:((. Thanks a lot for this info:>. Also, I only have 7408 gate:<<
You know that you can make any gate with just NAND gates? The same thing is true with NOR gates. That’s why those two are called Universal Gates. You can Google for the equivalent circuits.
 

Thread Starter

gelzky

Joined Dec 7, 2021
86
You know that you can make any gate with just NAND gates? The same thing is true with NOR gates. That’s why those two are called Universal Gates. You can Google for the equivalent circuits.
yes, thank you I am quite aware of that but I really need to practice my logic skills in applying them on my circuit. Also, I only have the TTL ones and the problem is I'm using a cmos counter and schmitt input. But I'll stick with the circuit suggested by mr gibbs:>.
 

Thread Starter

gelzky

Joined Dec 7, 2021
86
Hello:) just an update on my circuit :) I was able to make it work:>. It alarms when the counter reaches 9. I just used an AND gate and an Inverter since the Schmitt input is a cmos that is why I was not able to use it on input of 'e' and and that solved the problem:). Although, the buzzer sounds a bit glitchy and like it does not reach its full pitch if you know what I mean :D. But here is what my diagram looks like:>. My apology for having a messy circuit:<.
 

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Thread Starter

gelzky

Joined Dec 7, 2021
86
Congratulations You’ve been very cooperative and respectful. Did you learn a lot? I think you have.
Thank you so much sir :) I'm really grateful for everyone posted in this forum. And I'm looking forward to learn more here, also I'll be watching other threads :) . Again thank you so much :)
 
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