TTL R-S Flip-Flop 1
Électronique / Electronic
7400

It's possible to build an R-S flip-flop using NAND gates. This Project will prove it! (If your memory needs refreshing about how an R-S flipflop works, take a look back at Project An R-S flip-flop.

After you finish the wiring connections, put power ON. Either LED 1 or LED 2 will light up.

Take a long wire and touch terminals Set and Reset in turn. What happens to LED 1 and LED 2?

Can you guess which represents the set state and which represents the reset state?

When LED 2 lights up, the R-S flip-flop is in the set state. When LED 1 lights up, the R-S flip-flop is reset.

When you get the flip-flop set or reset, try removing the long wire from the circuit and see what happens. You see one of the prime characteristics of the R-S flip-flop, once the circuit is set or reset, the circuit keeps that state until an input signal causes it to change.

This means the R-S flip-flop can "remember" things. More advanced circuits like this one are used in computers so they can "remember" things as well.