My seven seg display wont show

[rlk8481]

I have attached my circut that I am having a problem with.  I am suppose to put in any binary code in and my seven seg display should show the decimal number.  My display isnt showing nothing at all. Thanks in advance if you can help me out.


Message Edited by rlk8481 on 04-05-2008 04:46 PM

[digitalguy]

Your display is a common cathode type and CK must be tied to ground.

Howard

[rlk8481]

so all i have to do is put ck to ground and it will work

[digitalguy]

Yes. I simply made that change and it worked fine (at least as far as the circuit is concerned - I'll leave it to you to determine if that's what you wanted)

Howard

[digitalguy]

Perhaps part of the problem is that the symbol used shows active low outputs when in actuality they are active high outputs. The symbol should not have the bubbles on the outputs.

Howard

[lacy]

I believe you to be correct about this even though it is simullating correctly the symbol is incorrect. The datasheet does not show these outputs to be active low. They are active high. Good catch on this one.

Also if you look at the 7447 it is also labled incorrectly. These 2 component symbols need to be swapped with each other.

Message Edited by lacy on 04-06-2008 06:43 PM

[lacy]

I made a mistake in my last post that I would like to rectify now. The 7447N  symbol is correct as is. I just failed to see the little circles on the outputs. This chip is active low so it is right. It is the 7448N symbol that is incorrect and should have the circles removed as these outputs are active high as previously stated by another forum user. Sorry about my mistake and I hope I didn't confuse anyone.