cant find a coomponent nor its multisim equivalent

[ngogketrao]

Hello again!
 Can you please tell me which IC to use in replacement for the 4026 (as i don't have the datasheet of this IC, hence i don't know its properties).

  Thank You

[lacy]

It is not one IC, but 2 of them. Granted this may not be exact as to the function of the 4026 but it might get close enough for you to use.

I just chose 2 IC's from the database and  put them together. You can use my circuit as a guide to find others that may be more suitable to you. The only drawback I see is the fact that most of the seven segment drivers are BCD meaning they can accept binary numbers from 0 to 9 (0000 to 1001) and then do not display anything above that. If you need to display hexadecimal numbers from A through F then this could be problematic and is something I am going to investigate further to see what can be done.

I will post the circuit below.

[ngogketrao]

thank you,
but actually i am trying to design a circuit to count the time but i don't seem to get it right. what CMOS ICs should i use?

[lacy]

Maybe you could post what you have so we can get a better idea of what your shooting for? This circuit will count time (like a cliock) if you adjust the input frequency to like say 1hz (1 pulse per second) in order to count seconds. You can also have it count up to hours by lowering this frequency even further.

[ngogketrao]

Good afternoon!

 Here I sent you a copy of the seconds display. I tried to simulate it but it doesn't work. I don't know what's wrong with it.

[lacy]

O.K. I got it working. My post is going to be quite lenghty as I encounter something strange  that I have no explaination for.

First, the 7447 IC's were incorrect for driving common cathode displays. I replaced these with 7448s. Also the RBI RBO and LT have to be tied high in order for these IC to work. These inputs are active low. This means that when they are at 0V they perform their function which in this case is blanking the display. Therefore nothing is diplayed until these are pulled high.

Now for the strange part. After doing everything in the previous paragraph the circuit still did not work. I clicked on the VCC attached to U3 and selected the value tab (why I wanted to do this I do not know, but I did). After that I pressed the O.K. button at the bottom of the dialog box. When I hit the simulation switch everything came up and ran like it should. Why this VCC was causing a problem I do not know. If you would like to try this yourself just do everything in the first paragraph and leave this VCC alone. Then click on it to bring up the properties and select the value tab. Then click the O.K. button. I do not have an explaination for this behaviour.

I will post the working circuit for you to examine, but try my prodedure on the original and see if you can replicate this strange VCC issue.  I would appreciate knowing if it happens on yours as well.

[ngogketrao]

 Good morning!
 Thank you for your response.
 I tried what you said and it worked at the first try. I don't understand why yours didn't work. I am now completing the design since I have to make a digital clock. I am simulating the clock now. For the seconds and minutes it works fine, but for the hours I have to wait because it is taking a long time. When I will finish testing and hopefully get it working, I will let you now.
 Have a good day!

[ngogketrao]

Good morning again!
 I am still simulating my clock and I think it will work, but I would like to have your opinion on it. What do you think can be wrong with it or what do you think I can change, or maybe how can I make it better? I will post it to you now.
  Thank you!

[lacy]

It works great. I let it run for a long time and all the displays seem to be in sync whith the timing i.e once 60 seconds is reached then the minutes switch over and so forth.

One thing to remember is that in reality the seconds portion would have to have an input clock pulse of 1Hz (if is is to be used to as a real time keeping type clock and not an event counter). I realize that you are using the higher frequency to speed up the simulation, but I thought it might be a good idea to make sure you remember to re-adjust this later..

You did an nice job designing and putting this together. Now that this portion is complete you can add whatever extras you desire to it.  One thing that you might want to look into is to a way of pre-setting the time (this is again dependent on it's application as a time keeper). Other than that little tidbit I have no further suggestions other than to have fun with it as it can be used now for a variety of application above and beyond a simple clock.

Great work.

[ngogketrao]

Good evening!

Thank you for taking your time to review my circuit. Now I will purchase the component and build it.
I will keep you posted on the results.

 Have a good day!