T type flip flop
We're going experiment with a T flip-flop. It has one input terminal and two output terminals. What do you suppose T stands for? You've already met... it's a "toggle" flip-flop.
When you finish the wiring for the project, turn power ON, tap S1 a few times and see what happens to LED 2. It blinks ON and OFF each time you tap S1. When you press S1 once, a pulse is input and the toggle flip-flop changes its state.
When you press it again, another pulse is input and this causes the flip-flop to return to the former state. The two output terminals of this circuit are pin 3 of IC3 and pin 6 of IC4. We are using only pin 6 of IC4 in this experiment, but note that these terminals have an inverse relationship with one other. When one of them is ON, the other is OFF, and vice versa.