# Building a circuit with 7400 chips

Discussion in 'Homework Help' started by needsomehelp, Jan 17, 2011.

1. ### needsomehelp Thread Starter New Member

Jan 17, 2011
7
0
I built a circuit accordingly and as shown in the second image:

http://img199.imageshack.us/img199/4293/scanj.gif
http://img585.imageshack.us/img585/6905/scan1.gif

The instructions at the end say I need to use 7400 chips.

Although I was able to figure out the drawing, I need help making the wiring schematic showing all the needed chips and connections. I have been trying to figure this out for quite some time and would greatly appreciate it if you could draw the chips out on paper connecting, them with lines. Thank you so much for your time and help with this! It will help me learn a lot.

2. ### Georacer Moderator

Nov 25, 2009
5,151
1,266
Are you supposed to implement the Boolean Functions from the first image with the 3 chips of the second image?
If so, can you explain your line of thoughts in order to accomplish this?

As I see it, the each NAND gate's output should represent one logic function. For example, the left one could be X and the right one Y.

That said, for the function X, the inputs of the corresponding NAND gate should be:
For D=1 (upper decoder) 2,6,7.
For D=0 (lower decoder) 0.

Can you see the logic behind that? Can you do the same for Y and repost a correct second page?
I 'll guide you on the wiring after you do that.

3. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
What further do you need? If you take the time to get data sheets for the logic IC's, then you can easily see what to do with unused inputs. Ground an Vcc are certainly easy enough.

Read the post above and give it a try.

4. ### thatoneguy AAC Fanatic!

Feb 19, 2009
6,357
718
Datasheets will let you know all you need for connecting:

74138

7420