SL Traffic light sequence


Joined Dec 29, 2010
From the schematic you can see that LS93 is a binary counter (NOT BCD) It counts from 0 to 15. As the first output was not used, the remaining 3 outputs would give you all the EVEN events ie 0,2,4,6....14.

The three LEDs namely /R, /A,/G are all active LOW so you have to create a truth table of the 3 colored LED against the 8 inputs 0...14.

Are you able to male the truth table yourself or you need more help?



Joined Mar 30, 2015
Welcome to AAC!

What does "SL" stand for?

Where did you come up with the restriction for the decode logic to be implemented with a quad 2 input NAND gate?

Do you understand that you need to use the full count from the counter?