Here's another counter circuit which can count up to three. It's called a sy nchronous counter, do you have any idea what that means?
And can you guess how It can count to three using only two LEDs?
Take a guess before building this Project.
Once you finish the wiring connections, put the power ON and watch the LEDs, Both LEDs are blinking.
When both LEDs are off, that stands for 1.
Then LED 2 will light while LED 1 will be off.
That's the same as 2.
Finally, LED 1 will light while LED 2 will be off. That's 3 - so this circuit can really count up to three.
You'll see the LEDs both go out after three is reached and the entire cycle will start over.
A synchronous counter is one where the clock signal is input to all flip-flops at the same time. You can see from the schematic that each flip-flop gets a clock signal directly from the multivibrator.
This is how we manage to keep the two flip-flops "in step" with each other, something very important in a counting circuit.