R-S-T flip flop
Electronic
7400

The R-S-T flip-flop circuit we're going explore in this project can reverse any seesaw-like action applied to it, and keep that reversed state. The schematic diagram shows that this circuit has three inputs (Set, Reset and Trigger) and two outputs (Q and Ǭ). The diagram indicates the relationship between these inputs and outputs.

Now, let's see how it works. Turn power ON and press S1 and S2. LED 1 lights up and LED 2 goes out.

When you press S2 and S3, LED 1 goes out and LED 2 lights up, and here you'll notice something.... yes, the circuit maintains this state. This means that the flip-flop can "remember" things. So, it's used in many different electronic devices such as memories, counters and so on.