Digital clock using 7490
7490 Pinout Let's look at the 7490 briefly to see how it works. Here is the pinout: The 7490 is a decade counter , meaning it is able to count from 0 to 9 cyclically, and that is its natural mode. That is, QA, QB, QC and QD are 4 bits in a binary number, and these pins cycle through 0 to 9, QD QC QB QA 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 0 1 1 1 1 0 0 0 1 0 0 1 You can also set the chip up to count up to other maximum n...