Modulo 3 Counter Design and Circuit

A modulo 3 (MOD-3) counter can be made using three D-type flip-flops. We simply look for the count of 3 which is 011 in binary. In this type of counter application, this is the only time when those bits will be 1’s at the same time, therefore we simply feed them into an AND gate to generate the RESET control signal. When the counter reaches this number, the output from the AND gate will initiate a reset on all the D-type flip-flops, and the count will begin again.

Although in this diagram there are three counters, only two are required to count to three, however occasionally professors like to show three counters to make it appear more difficult than it is.