Multiple counter
Électronique / Electronic
7400, 7476

It's not very handy having a separate counter for counting by 2, 3, 4 or some other number. You might be wondering if there's some way to have a counter circuit capable of counting up to several different numbers. Yes, there is such a circuit — and were going to build it right now.

You can see from the schematic that the pulses to be counted are generated by a multivibrator circuit. The counter itself is synchronous, since each flip-flop receives a clock signal directly from the multivibrator.

Put the power ON. Now put the selector at 2. You'll see that LED 1 and LED 2 take turns lighting, indicating that this Project is functioning as a "divide by 2" (or binary) counter.

Next put the selector at 3. Now you can see that LED 1, LED 2 and LED 3 will light up one after the other. This indicates that the circuit is now a divide by 3 counter.

Finally, put the selector at 4 and youll see all four LEDs light in turn. This indicates the Project is now a divide by 4 counter.

This Project shows how counters can be made to cover a wide range of counting rates. More complex counters using this same basic circuit are very important pieces of electronic equipment.