MOD-36 COUNTER

Step 1: Find out how many stages you need

Using either the "final count" or "mod-n" inequalities on page 3, we find that we would need 6 T-Flip Flops. Remember that the easiest way to solve either of the inequalities, provided no scientific calculator is present, is by counting up... 2, 4, 8, 16, 32, 64.

Step 2: Create a Generic Base-2 Counter

Despite the initial hesitation from some people, the schematic below is not at all functionally different from what was seen in the previous pages. I have chosen to put three of the required stages below to avoid having the web page stretch too far in the horizontal direction.

Step 3: Create a Comparison Table

Step 4: Insert in the Required Gates

Step 5: Wire up to the Final Count

MOD-21 COUNTER

Step 1: Find out how many stages you need

Using either the "final count" or "mod-n" inequalities on page 3, we find that we would need 5 T-Flip Flops.

Step 2: Create a Generic Base-2 Counter

Step 3: Create a Comparison Table

Step 4: Insert in the Required Gates

Step 5: Wire up to the Final Count

MOD-64 COUNTER

Step 1: Find out how many stages you need

Using either the "final count" or "mod-n" inequalities on page 3, we find that we would need 6 T-Flip Flops.

Step 2: Create a Generic Base-2 Counter

Since this is a mod-2^n counter, we are done at this step.

MOD-8 COUNTER WITH A RETURN TO 1

Step 1: Find out how many stages you need

Using either the "final count" or "mod-n" inequalities on page 3, we find that we would need 3 T-Flip Flops.

Step 2: Create a Generic Base-2 Counter

Step 3: Create a Comparison Table

Step 4: Insert in the Required Gates

Step 5: Wire up to the Final Count

As an alternative, the schematic can be further simplified by changing the 3-input AND gate to a 2-input one because we already have an AND gate that ANDs both the first and second stage.

MOD-21 COUNTER WITH A RETURN TO 7

Step 1: Find out how many stages you need

Using either the "final count" or "mod-n" inequalities on page 3, we find that we would need 5 T-Flip Flops.

Step 2: Create a Generic Base-2 Counter

Step 3: Create a Comparison Table

Step 4: Insert in the Required Gates

Step 5: Wire up to the Final Count